Develop Reference

Separating Axis Theorem Implementation always returning true. What am I doing wrong?

I'm trying to implement collision detection for concave polygons in Javascript/p5.js using the Separating Axis Theorem. I've been following the following tutorial on how to use it: http://www.dyn4j.org/2010/01/sat/
However, my check is always returning true, no matter the positioning of the two polygons. Here's my code:
function SAT(shape1, shape2)
{
let axes1 = getAxes(shape1);
let axes2 = getAxes(shape2);
let colliding = true;
for (let i = 0; i < axes1.length; i++)
{
let axis = axes1[i];
let p1 = shape1.project(axis);
let p2 = shape2.project(axis);
if (!p1.overlap(p2)) colliding = false;
}
for (let i = 0; i < axes2.length; i++)
{
let axis = axes2[i];
let p1 = shape1.project(axis);
let p2 = shape2.project(axis);
if (!p1.overlap(p2)) colliding = false;
}
return colliding;
}
function getAxes(shape)
{
let axes = [];
for (let i = 0; i < shape.vertices.length; i++)
{
let p1 = shape.vertices[i];
let p2 = shape.vertices[i + 1 == shape.vertices.length ? 0 : i + 1];
let edge = p1.sub(p2);
let normal = createVector(-edge.y, edge.x);
axes[i] = normal;
}
return axes;
}
class Projection
{
constructor(min, max)
{
this.min = min;
this.max = max;
}
overlap(other)
{
if (this.max < other.min || other.max < this.min) return false;
else return true;
}
}
class PolygonCollider extends Component
{
constructor(gameObject)
{
super(gameObject);
this.untransformedVertices = [];
this.vertices = [];
...
}
setVerts(verts)
{
if (verts && verts.length > 2)
{
this.untransformedVertices = verts;
this.vertices = this.transform.getTransformedPoints(verts);
return this;
}
else return false;
}
project(axis)
{
let min = axis.dot(this.vertices[0]);
let max = min;
for (let i = 1; i < this.vertices.length; i++)
{
let p = axis.dot(this.vertices[i]);
if (p < min) min = p;
else if (p > max) max = p;
}
return new Projection(min, max);
}
update()
{
this.vertices = this.transform.getTransformedPoints(this.untransformedVertices);
}
...
}
Vertices are transformed with the following function, using a defined scale, rotation and position:
getTransformedPoints(points)
{
let transformed = [];
for (let i = 0; i < points.length; i++)
{
let rX = ((this.scale.x * points[i].x) * Math.cos(this.rotation)) - ((this.scale.y * points[i].y) * Math.sin(this.rotation));
let rY = ((this.scale.x * points[i].x) * Math.sin(this.rotation)) + ((this.scale.y * points[i].y) * Math.cos(this.rotation));
transformed[i] = createVector(rX + this.position.x, rY + this.position.y);
}
return transformed;
}
The SAT method is always returning true. I believe I'm checking for the overlap incorrectly, but I can't figure out what exactly I'm doing wrong.

So, it turns out the issue with my implementation lied with p5.js, a library I am using in this case.
In the getAxes method, I was subtracting p1 from p2 using p5's built in p5.Vector.sub function. This didn't have the desired effect. I'm not sure, but I believe the issue was that it wasn't creating a new vector that was the difference of the equation. I fixed this simply by creating the new vector myself as such: createVector(p2.x - p1.x, p2.y - p1.y);

Subset sum with number reuse allowed

I have a list of positive integers e.g. 15, 29, 110, and a target e.g. 44. I'm trying to find all possible combinations which sum to the target but importantly, the numbers in the set can be used multiple times e.g.
Target = 44
Result = 1x15, 1x29
Target = 307
Result = 2x110, 3x29
I found a dynamic programming solution which works when the combination is no more than one of each number. So Target 44 works but not my 307 example (returns Not Found).
How can the multiples or number reuse be done?
function subset(people, min, max)
{
var subsets = [];
subsets[0] = '';
for (var person in people)
{
for (var s = min-1; s >= 0; --s)
{
if (s in subsets)
{
var sum = s + people[person];
if (!(sum in subsets))
{
subsets[sum] = subsets[s] + ' ' + person;
if (sum >= min && sum <= max)
{
return subsets[sum];
}
}
}
}
}
return 'Not found';
}
var p = {
optionA:15,
optionB:29,
optionC:110
};
var qty = 307;
console.log(subset(p, qty, qty));

Try this recursive solution:
function subset(people, min, max) {
const pairs = Object.entries(people),
results = [],
getSum = multiplications => multiplications.reduce((sum, multiplicator, position) =>
sum + pairs[position][1] * multiplicator, 0),
formatResult = result => result.map(multiplications =>
multiplications.reduce((res, multiplicator, position) =>
(multiplicator > 0 ? res.push(`${multiplicator}x${pairs[position][1]}`) :
res, res), []));
function findSums(multiplications, position) {
let s;
while((s = getSum(multiplications)) <= max) {
if (s >= min) {
results.push([...multiplications]);
}
if (position < pairs.length - 1) {
const m = [...multiplications],
nextPosition = position + 1;
m[nextPosition]++;
findSums(m, nextPosition);
}
multiplications[position]++;
}
}
findSums(pairs.map(_ => 0), 0);
return results.length > 0 ? formatResult(results) : "Not found";
}
var p = {
optionA:15,
optionB:29,
optionC:110
};
var qty = 307;
console.log(subset(p, qty, qty));

Change the second loop in such way:
for (var s = 0; s <= wantedSum - people[person] ; s++)
Using this approach you fill all entries of subsets[] array\list where index is multiple of people[person] (instead of single entry). For example, with value 3 you fill 3,6,9,12... entries.

Javascript String Manipulation and Conversion with Range

I have a string like this (must be in this format):
var string = "[0] No new notifications | [1,] Some new notifications"
And I want to get "No new notifications" if a variable is 0 and if that variable is 1 or greater, show "Some new notifications".
How can I do that?

Here's a generic processesor for ISO 31-11 strings. It takes the ISO 31-11 string and the numeric value, then returns the appropriate string or undefined. Here's a fiddle.
function processISO31_11(rangeGuide, n) {
var separator = /\[(\d+)(,)?(\d+)?\]\s?(.+)/;
var rangeGuides = rangeGuide.split('|');
var guideCount = rangeGuides.length;
for (var guide = 0; guide < guideCount; guide++) {
var elements = separator.exec(rangeGuides[guide]);
if (elements != null) {
if (n < parseFloat(elements[1])) {
return; // return undefined indicating failure to match any range
}
if (n == parseFloat(elements[1])) {
return elements[4];
}
if (elements[2] === "," && (typeof elements[3] === "undefined" || n <= parseFloat(elements[3]))) {
return elements[4];
}
}
}
}

var somevar = 3;
var yourString = '[0] No new notifications | [1,] Some new notifications';
var notification = yourString .split(' | ');
var message=(somevar == 0 ? notification[0].split('] ')[1] : notification[1].split('] ')[1]);
the var message has your needed output.

After examining more closely exactly what you are looking for, I have come up with a solution that will read in the rules you pass it and essentially turn that into logic that your program will follow. Here is a demo of how it would work:
var myVar = 3;
var myStr = '[0] No new notifications | [1,4] Some new notifications | [5,] Several new notifications';
var notificationRules = getRules(myStr);
function getRules(rulesString) {
return rulesString.split(' | ').map(function(rule) {
var startValue, endValue;
var values = rule.match(/\[\d*,?\d*\]/g)[0];
values = values.replace(/\[|\]/g, "").split(",");
startValue = values[0];
endValue = +values[1] === 0 ? Infinity : values[1];
return {
startValue: Number(startValue),
endValue: endValue != undefined ? Number(endValue) : undefined,
message: rule.replace(/\[\d*,?\d*\]/g, "").trim()
};
});
}
function getMessage(myVar, rules) {
var message = "No rule match!";
rules.some(function(rule) {
if (myVar === rule.startValue) {
message = rule.message;
return true;
} else if (myVar >= rule.startValue && myVar <= rule.endValue) {
message = rule.message;
}
});
return message;
}
console.log(getMessage(0, notificationRules));
console.log(getMessage(2, notificationRules));
console.log(getMessage(5, notificationRules));
console.log(getMessage(100, notificationRules));
console.log(getMessage(-1, notificationRules));

Complex solution using String.prototype.split(), String.prototype.match() and String.prototype.slice() functions:
var configStr = '[0] No new notifications | [1,] Some new notifications',
getNotifyMessage = function (config, num) {
var num = Number(num),
items = config.split('|'),
len = items.length, parts;
while (len--) {
parts = items[len].match(/\[(\d+,?)\]\s([\w ]+)(?=\||$)/i);
if (Number(parts[1]) === num) {
return parts[2];
}
if (parts[1].slice(-1) === ',' && Number(parts[1].slice(0,-1)) <= num) {
return parts[2];
}
}
return '';
};
console.log(getNotifyMessage(configStr, 1));
console.log(getNotifyMessage(configStr, 0));
console.log(getNotifyMessage(configStr, 3));

How do you return the resulting object in a function?

Good day, all! :)
For the past month, I have been working on a function to return 2 or more THREE.js materials in 1 function at 1 time. I've run into a small problem though. For some reason, I can't get this function to return the MeshBasicMaterial object AS WELL AS the MeshLambertMaterial data object. I KNOW my code is right because I've gone over it over 40 times already looking for errors.
Here's the WHOLE code:
/**
* A function for converting hex <-> dec w/o loss of precision.
*
* The problem is that parseInt("0x12345...") isn't precise enough to convert
* 64-bit integers correctly.
*
* Internally, this uses arrays to encode decimal digits starting with the least
* significant:
* 8 = [8]
* 16 = [6, 1]
* 1024 = [4, 2, 0, 1]
*/
// Adds two arrays for the given base (10 or 16), returning the result.
// This turns out to be the only "primitive" operation we need.
function add(x, y, base)
{
var z = [];
var n = Math.max(x.length, y.length);
var carry = 0;
var i = 0;
while (i < n || carry)
{
var xi = i < x.length ? x[i] : 0;
var yi = i < y.length ? y[i] : 0;
var zi = carry + xi + yi;
z.push(zi % base);
carry = Math.floor(zi / base);
i++;
}
return z;
}
// Returns a*x, where x is an array of decimal digits and a is an ordinary
// JavaScript number. base is the number base of the array x.
function multiplyByNumber(num, x, base)
{
if (num < 0) return null;
if (num == 0) return [];
var result = [];
var power = x;
while (true)
{
if (num & 1)
{
result = add(result, power, base);
}
num = num >> 1;
if (num === 0) break;
power = add(power, power, base);
}
return result;
}
function parseToDigitsArray(str, base)
{
var digits = str.split('');
var ary = [];
for (var i = digits.length - 1; i >= 0; i--)
{
var n = parseInt(digits[i], base);
if (isNaN(n)) return null;
ary.push(n);
}
return ary;
}
function convertBase(str, fromBase, toBase)
{
var digits = parseToDigitsArray(str, fromBase);
if (digits === null) return null;
var outArray = [];
var power = [1];
for (var i = 0; i < digits.length; i++)
{
// invariant: at this point, fromBase^i = power
if (digits[i])
{
outArray = add(outArray, multiplyByNumber(digits[i], power, toBase), toBase);
}
power = multiplyByNumber(fromBase, power, toBase);
}
var out = '';
for (var i = outArray.length - 1; i >= 0; i--)
{
out += outArray[i].toString(toBase);
}
return out;
}
function decToHex(decStr) {
var hex = convertBase(decStr, 10, 16);
return hex ? '0x' + hex : null;
}
function hexToDec(hexStr) {
if (hexStr.substring(0, 2) === '0x') hexStr = hexStr.substring(2);
hexStr = hexStr.toLowerCase();
return convertBase(hexStr, 16, 10);
}
function instr(str, val)
{
if(typeof(str) === 'string')
{
str = str.toString(str);
val = val.toString(val);
in_str = str.indexOf(val);
return in_str;
}
else
{
api_messagebox('Please use a string!');
}
return false;
}
function Get_RGBA(hexVal, getwhich)
{
hexVal = hexVal || '';
getwhich = getwhich || 0;
var commaSeperated = 0;
//if(typeof(hexVal) === 'string')
//{
// Removes the first character from the input string
if(hexVal.length === 8) { hexVal = hexVal.substring(1, hexVal.length); }
if(hexVal.length === 10) { hexVal = hexVal.substring(0, hexVal.length); }
// Now let's separate the pairs by a comma
for (var i = 0; i <= hexVal.length; i++)
{
// Iterate through each char of hexVal
// Copy each char of hexVal to commaSeperated
commaSeperated += hexVal.charAt(i);
// After each pair of characters add a comma, unless this
// is the last char
commaSeperated += (i % 2 == 1 && i != (hexVal.length - 1)) ? ',' : '';
}
// Lets now remove the 0x
if(instr(commaSeperated, '0x'))
{
commaSeperated = commaSeperated.substr(4);
}
if(instr(commaSeperated, ','))
{
// Lets now remove all "," 's
commaSeperated = commaSeperated.replace(/,/g, '');
if( getwhich < 0 ) { getwhich = 0; }
if( getwhich > 5 ) { getwhich = 5; }
alpha = [];
red = [];
green = [];
blue = [];
allcol = [];
sixcol = [];
alpha[0] = commaSeperated[0]+commaSeperated[1];
red[0] = commaSeperated[2]+commaSeperated[3];
green[0] = commaSeperated[4]+commaSeperated[5];
blue[0] = commaSeperated[6]+commaSeperated[7];
allcol[0] = alpha[0]+red[0]+green[0]+blue[0];
sixcol[0] = red[0]+green[0]+blue[0];
if( getwhich === 0 ) { fi_string = alpha[0]; }
if( getwhich === 1 ) { fi_string = red[0]; }
if( getwhich === 2 ) { fi_string = green[0]; }
if( getwhich === 3 ) { fi_string = blue[0]; }
if( getwhich === 4 ) { fi_string = allcol[0]; }
if( getwhich === 5 ) { fi_string = sixcol[0]; }
if( getwhich === 4 && fi_string.length != 10 || fi_string.length != 9 ) { getwhich = 5; }
if( getwhich === 5 && fi_string.length != 8 || fi_string.length != 7 ) { getwhich = 4; }
// Split the commaSeperated string by commas and return the array
return fi_string.toString();
}
//}
}
function isArray(myArray)
{
return myArray.constructor.toString();
//myArray.constructor.toString().indexOf("Array") > -1;
}
//EntityMaterial(0, 0, 0xFF44CFFC, 1, 0xFF000000, 4, 4, 0, 1.0, 0.8, "LambertBasicMaterial", 1)
function EntityMaterial(ptex, side, color, wire, wirecolor, col_type, col_wire_type, shading, transparent, opacity, mat_type, overdraw)
{
ptex = ptex || 0;
side = side || 0;
color = color || 0xFF006400;
wire = wire || 0;
wirecolor = wirecolor || 0xFF006400;
col_type = col_type || 4;
col_wire_type = col_wire_type || 4;
shading = shading || false;
transparent = transparent || 0.0;
opacity = opacity || 1.0;
mat_type = mat_type || "BasicMaterial";
overdraw = overdraw || true;
color = decToHex(color.toString());
wirecolor = decToHex(wirecolor.toString());
var gRGBA1 = Get_RGBA(color, col_type);
var gRGBA2 = Get_RGBA(wirecolor, col_wire_type);
var mat = 0;
if(mat_type === 'BasicMaterial')
{
this.materials = new THREE.MeshBasicMaterial
(
{
color: parseInt(gRGBA1, 16)
}
)
}
else if(mat_type === 'LambertMaterial')
{
this.materials = new THREE.MeshLambertMaterial
(
{
color: parseInt(gRGBA2, 16),
opacity: opacity,
wireframe: wire,
transparent: transparent
}
)
}
else if(mat_type === 'LambertBasicMaterial')
{
//new empty array.. could also be written as this.materials = new Array();
this.materials = [];
var mats = this.materials;
var basicMat = new THREE.MeshBasicMaterial( { color: parseInt(gRGBA1, 16) } );
var lambertMat = new THREE.MeshLambertMaterial( { color: parseInt(gRGBA2, 16), opacity: opacity, wireframe: wire, transparent: transparent } );
mats.push(basicMat);
mats.push(lambertMat);
api_messagebox(mats);
return mats;
}
}
Thank you so much!
Sincerely,
~Mythros

Right, I finally got around to trying it out and it all runs well for me.
To make sure we don't have any differences in environments take a look at the fiddle I made and let me know if it works for you as expected or if there's any other problems you need help with:
JSFiddle of original code
Small changes:
commented out the
api_messagebox(mats)
as it's undefined.
added lots of log statements so check out the web console.
Edit
I fixed the color problem by using THree.js' Color object as follows:
var color = new THREE.Color("rgb(0,0,255)");
But you may be doing this somewhere as the GET_RGBA function you are calling seems to be missing from the code you gave me.
As to making it wiremesh, I checked the Lambert object and it definitely had wiremesh = 1 set.
Make sure that the wire var you're passing is actually set to true, I set it explicitly in this updated fiddle

Compare Strings Javascript Return %of Likely

I am looking for a JavaScript function that can compare two strings and return the likeliness that they are alike. I have looked at soundex but that's not really great for multi-word strings or non-names. I am looking for a function like:
function compare(strA,strB){
}
compare("Apples","apple") = Some X Percentage.
The function would work with all types of strings, including numbers, multi-word values, and names. Perhaps there's a simple algorithm I could use?
Ultimately none of these served my purpose so I used this:
function compare(c, u) {
var incept = false;
var ca = c.split(",");
u = clean(u);
//ca = correct answer array (Collection of all correct answer)
//caa = a single correct answer word array (collection of words of a single correct answer)
//u = array of user answer words cleaned using custom clean function
for (var z = 0; z < ca.length; z++) {
caa = $.trim(ca[z]).split(" ");
var pc = 0;
for (var x = 0; x < caa.length; x++) {
for (var y = 0; y < u.length; y++) {
if (soundex(u[y]) != null && soundex(caa[x]) != null) {
if (soundex(u[y]) == soundex(caa[x])) {
pc = pc + 1;
}
}
else {
if (u[y].indexOf(caa[x]) > -1) {
pc = pc + 1;
}
}
}
}
if ((pc / caa.length) > 0.5) {
return true;
}
}
return false;
}
// create object listing the SOUNDEX values for each letter
// -1 indicates that the letter is not coded, but is used for coding
// 0 indicates that the letter is omitted for modern census archives
// but acts like -1 for older census archives
// 1 is for BFPV
// 2 is for CGJKQSXZ
// 3 is for DT
// 4 is for L
// 5 is for MN my home state
// 6 is for R
function makesoundex() {
this.a = -1
this.b = 1
this.c = 2
this.d = 3
this.e = -1
this.f = 1
this.g = 2
this.h = 0
this.i = -1
this.j = 2
this.k = 2
this.l = 4
this.m = 5
this.n = 5
this.o = -1
this.p = 1
this.q = 2
this.r = 6
this.s = 2
this.t = 3
this.u = -1
this.v = 1
this.w = 0
this.x = 2
this.y = -1
this.z = 2
}
var sndx = new makesoundex()
// check to see that the input is valid
function isSurname(name) {
if (name == "" || name == null) {
return false
} else {
for (var i = 0; i < name.length; i++) {
var letter = name.charAt(i)
if (!(letter >= 'a' && letter <= 'z' || letter >= 'A' && letter <= 'Z')) {
return false
}
}
}
return true
}
// Collapse out directly adjacent sounds
// 1. Assume that surname.length>=1
// 2. Assume that surname contains only lowercase letters
function collapse(surname) {
if (surname.length == 1) {
return surname
}
var right = collapse(surname.substring(1, surname.length))
if (sndx[surname.charAt(0)] == sndx[right.charAt(0)]) {
return surname.charAt(0) + right.substring(1, right.length)
}
return surname.charAt(0) + right
}
// Collapse out directly adjacent sounds using the new National Archives method
// 1. Assume that surname.length>=1
// 2. Assume that surname contains only lowercase letters
// 3. H and W are completely ignored
function omit(surname) {
if (surname.length == 1) {
return surname
}
var right = omit(surname.substring(1, surname.length))
if (!sndx[right.charAt(0)]) {
return surname.charAt(0) + right.substring(1, right.length)
}
return surname.charAt(0) + right
}
// Output the coded sequence
function output_sequence(seq) {
var output = seq.charAt(0).toUpperCase() // Retain first letter
output += "-" // Separate letter with a dash
var stage2 = seq.substring(1, seq.length)
var count = 0
for (var i = 0; i < stage2.length && count < 3; i++) {
if (sndx[stage2.charAt(i)] > 0) {
output += sndx[stage2.charAt(i)]
count++
}
}
for (; count < 3; count++) {
output += "0"
}
return output
}
// Compute the SOUNDEX code for the surname
function soundex(value) {
if (!isSurname(value)) {
return null
}
var stage1 = collapse(value.toLowerCase())
//form.result.value=output_sequence(stage1);
var stage1 = omit(value.toLowerCase())
var stage2 = collapse(stage1)
return output_sequence(stage2);
}
function clean(u) {
var u = u.replace(/\,/g, "");
u = u.toLowerCase().split(" ");
var cw = ["ARRAY OF WORDS TO BE EXCLUDED FROM COMPARISON"];
var n = [];
for (var y = 0; y < u.length; y++) {
var test = false;
for (var z = 0; z < cw.length; z++) {
if (u[y] != "" && u[y] != cw[z]) {
test = true;
break;
}
}
if (test) {
//Don't use & or $ in comparison
var val = u[y].replace("$", "").replace("&", "");
n.push(val);
}
}
return n;
}

Here's an answer based on Levenshtein distance https://en.wikipedia.org/wiki/Levenshtein_distance
function similarity(s1, s2) {
var longer = s1;
var shorter = s2;
if (s1.length < s2.length) {
longer = s2;
shorter = s1;
}
var longerLength = longer.length;
if (longerLength == 0) {
return 1.0;
}
return (longerLength - editDistance(longer, shorter)) / parseFloat(longerLength);
}
For calculating edit distance
function editDistance(s1, s2) {
s1 = s1.toLowerCase();
s2 = s2.toLowerCase();
var costs = new Array();
for (var i = 0; i <= s1.length; i++) {
var lastValue = i;
for (var j = 0; j <= s2.length; j++) {
if (i == 0)
costs[j] = j;
else {
if (j > 0) {
var newValue = costs[j - 1];
if (s1.charAt(i - 1) != s2.charAt(j - 1))
newValue = Math.min(Math.min(newValue, lastValue),
costs[j]) + 1;
costs[j - 1] = lastValue;
lastValue = newValue;
}
}
}
if (i > 0)
costs[s2.length] = lastValue;
}
return costs[s2.length];
}
Usage
similarity('Stack Overflow','Stack Ovrflw')
returns 0.8571428571428571
You can play with it below:
function checkSimilarity(){
var str1 = document.getElementById("lhsInput").value;
var str2 = document.getElementById("rhsInput").value;
document.getElementById("output").innerHTML = similarity(str1, str2);
}
function similarity(s1, s2) {
var longer = s1;
var shorter = s2;
if (s1.length < s2.length) {
longer = s2;
shorter = s1;
}
var longerLength = longer.length;
if (longerLength == 0) {
return 1.0;
}
return (longerLength - editDistance(longer, shorter)) / parseFloat(longerLength);
}
function editDistance(s1, s2) {
s1 = s1.toLowerCase();
s2 = s2.toLowerCase();
var costs = new Array();
for (var i = 0; i <= s1.length; i++) {
var lastValue = i;
for (var j = 0; j <= s2.length; j++) {
if (i == 0)
costs[j] = j;
else {
if (j > 0) {
var newValue = costs[j - 1];
if (s1.charAt(i - 1) != s2.charAt(j - 1))
newValue = Math.min(Math.min(newValue, lastValue),
costs[j]) + 1;
costs[j - 1] = lastValue;
lastValue = newValue;
}
}
}
if (i > 0)
costs[s2.length] = lastValue;
}
return costs[s2.length];
}
<div><label for="lhsInput">String 1:</label> <input type="text" id="lhsInput" oninput="checkSimilarity()" /></div>
<div><label for="rhsInput">String 2:</label> <input type="text" id="rhsInput" oninput="checkSimilarity()" /></div>
<div>Match: <span id="output">No Input</span></div>

Using this library for string similarity worked like a charm for me!
Here's the Example -
var similarity = stringSimilarity.compareTwoStrings("Apples","apple"); // => 0.88

Here is a very simple function that does a comparison and returns a percentage based on equivalency. While it has not been tested for all possible scenarios, it may help you get started.
function similar(a,b) {
var equivalency = 0;
var minLength = (a.length > b.length) ? b.length : a.length;
var maxLength = (a.length < b.length) ? b.length : a.length;
for(var i = 0; i < minLength; i++) {
if(a[i] == b[i]) {
equivalency++;
}
}
var weight = equivalency / maxLength;
return (weight * 100) + "%";
}
alert(similar("test","tes")); // 75%
alert(similar("test","test")); // 100%
alert(similar("test","testt")); // 80%
alert(similar("test","tess")); // 75%

To Find degree of similarity between two strings; we can use more than one or two methods but I am mostly inclined towards the usage of 'Dice's Coefficient' . which is better! well in my knowledge than using 'Levenshtein distance'
Using this 'string-similarity' package from npm you will be able to work on what I said above.
some easy usage examples are
var stringSimilarity = require('string-similarity');
var similarity = stringSimilarity.compareTwoStrings('healed', 'sealed');
var matches = stringSimilarity.findBestMatch('healed', ['edward', 'sealed', 'theatre']);
for more please visit the link given above. Thankyou.

Just one I quickly wrote that might be good enough for your purposes:
function Compare(strA,strB){
for(var result = 0, i = strA.length; i--;){
if(typeof strB[i] == 'undefined' || strA[i] == strB[i]);
else if(strA[i].toLowerCase() == strB[i].toLowerCase())
result++;
else
result += 4;
}
return 1 - (result + 4*Math.abs(strA.length - strB.length))/(2*(strA.length+strB.length));
}
This weighs characters that are the same but different case 1 quarter as heavily as characters that are completely different or missing. It returns a number between 0 and 1, 1 meaning the strings are identical. 0 meaning they have no similarities. Examples:
Compare("Apple", "Apple") // 1
Compare("Apples", "Apple") // 0.8181818181818181
Compare("Apples", "apple") // 0.7727272727272727
Compare("a", "A") // 0.75
Compare("Apples", "appppp") // 0.45833333333333337
Compare("a", "b") // 0

How about function similar_text from PHP.js library?
It is based on a PHP function with the same name.
function similar_text (first, second) {
// Calculates the similarity between two strings
// discuss at: http://phpjs.org/functions/similar_text
if (first === null || second === null || typeof first === 'undefined' || typeof second === 'undefined') {
return 0;
}
first += '';
second += '';
var pos1 = 0,
pos2 = 0,
max = 0,
firstLength = first.length,
secondLength = second.length,
p, q, l, sum;
max = 0;
for (p = 0; p < firstLength; p++) {
for (q = 0; q < secondLength; q++) {
for (l = 0;
(p + l < firstLength) && (q + l < secondLength) && (first.charAt(p + l) === second.charAt(q + l)); l++);
if (l > max) {
max = l;
pos1 = p;
pos2 = q;
}
}
}
sum = max;
if (sum) {
if (pos1 && pos2) {
sum += this.similar_text(first.substr(0, pos2), second.substr(0, pos2));
}
if ((pos1 + max < firstLength) && (pos2 + max < secondLength)) {
sum += this.similar_text(first.substr(pos1 + max, firstLength - pos1 - max), second.substr(pos2 + max, secondLength - pos2 - max));
}
}
return sum;
}

fuzzyset - A fuzzy string set for javascript.
fuzzyset is a data structure that performs something akin to fulltext search against data to determine likely mispellings and approximate string matching. Note that this is a javascript port of a python library.

To some extent, I like the ideas of Dice's coefficient embedded in the string-similarity module. But I feel that considering the bigrams only and not taking into account their multiplicities is missing some important data. Below is a version that also handles multiplicities, and I think is a simpler implementation overall. I don't try to use their API, offering only a function which compares two strings after some manipulation (removing non-alphanumeric characters, lower-casing everything, and compressing but not removing whitespace), built atop one which compares them without that manipulation. It would be easy enough to wrap this back in their API, but I see little need.
const stringSimilarity = (a, b) =>
_stringSimilarity (prep (a), prep (b))
const _stringSimilarity = (a, b) => {
const bg1 = bigrams (a)
const bg2 = bigrams (b)
const c1 = count (bg1)
const c2 = count (bg2)
const combined = uniq ([... bg1, ... bg2])
.reduce ((t, k) => t + (Math .min (c1 [k] || 0, c2 [k] || 0)), 0)
return 2 * combined / (bg1 .length + bg2 .length)
}
const prep = (str) => // TODO: unicode support?
str .toLowerCase () .replace (/[^\w\s]/g, ' ') .replace (/\s+/g, ' ')
const bigrams = (str) =>
[...str] .slice (0, -1) .map ((c, i) => c + str [i + 1])
const count = (xs) =>
xs .reduce ((a, x) => ((a [x] = (a [x] || 0) + 1), a), {})
const uniq = (xs) =>
[... new Set (xs)]
console .log (stringSimilarity (
'foobar',
'Foobar'
)) //=> 1
console .log (stringSimilarity (
"healed",
"sealed"
))//=> 0.8
console .log (stringSimilarity (
"Olive-green table for sale, in extremely good condition.",
"For sale: table in very good condition, olive green in colour."
)) //=> 0.7787610619469026
console .log (stringSimilarity (
"Olive-green table for sale, in extremely good condition.",
"For sale: green Subaru Impreza, 210,000 miles"
)) //=> 0.38636363636363635
console .log (stringSimilarity (
"Olive-green table for sale, in extremely good condition.",
"Wanted: mountain bike with at least 21 gears."
)) //=> 0.1702127659574468
console .log (stringSimilarity (
"The rain in Spain falls mainly on the plain.",
"The run in Spun falls munly on the plun.",
)) //=> 0.7560975609756098
console .log (stringSimilarity (
"Fa la la la la, la la la la",
"Fa la la la la, la la",
)) //=> 0.8636363636363636
console .log (stringSimilarity (
"car crash",
"carcrash",
)) //=> 0.8
console .log (stringSimilarity (
"Now is the time for all good men to come to the aid of their party.",
"Huh?",
)) //=> 0
.as-console-wrapper {max-height: 100% !important; top: 0}
Some of the test cases are from string-similarity, others are my own. They show some significant differences from that package, but nothing untoward. The only one I would call out is the difference between "car crash" and "carcrash", which string-similarity sees as identical and I report with a similarity of 0.8. My version finds more similarity in all the olive-green test-cases than does string-similarity, but as these are in any case fairly arbitrary numbers, I'm not sure how much difference it makes; they certainly position them in the same relative order.

string-similarity lib vs Top answer (by #overloard1234) performance comparation you can find below
Based on #Tushar Walzade's advice to use string-similarity library, you can find, that for example
stringSimilatityLib.findBestMatch('KIA','Kia').bestMatch.rating
will return 0.0
So, looks like better to compare it in lowerCase.
Better base usage (for arrays) :
findBestMatch(str, strArr) {
const lowerCaseArr = strArr.map(element => element.toLowerCase());//creating lower case array
const match = stringSimilatityLib.findBestMatch(str.toLowerCase(), lowerCaseArr).bestMatch; //trying to find bestMatch
if (match.rating > 0) {
const foundIndex = lowerCaseArr.findIndex(x => x === match.target); //finding the index of found best case
return strArr[foundIndex]; //returning initial value from array
}
return null;
},
Performance
Also, i compared top answer here (made by #overloard1234) and string-similarity lib (v4.0.4).
The results you can find here : https://jsbench.me/szkzojoskq/1
Result : string-similarity is ~ twice faster
Just for fun : v2.0 of string-similarity library slower, than latest 4.0.4 about 2.2 times. So update it, if you are still using < 3.0 :)

const str1 = " pARTH PARmar r ";
const str2 = " parmar r par ";
function calculateSimilarity(str1 = "", str2 = "") {
let longer = str1.trim();
let shorter = str2.trim();
let a1 = longer.toLowerCase().split(" ");
let b1 = shorter.toLowerCase().split(" ");
let result = a1.every((aa, i) => aa[0] === b1[i][0]);
if (longer.length < shorter.length) [longer,shorter] = [shorter,longer];
var arr = [];
let count = 0;
for(var i = 0;i<longer.length;i++){
if(shorter && shorter.includes(longer[i])) {
shorter = shorter.replace(longer[i],"")
count++
};
}
return {
score : (count*100)/longer.length,
result
}
}
console.log(calculateSimilarity(str1, str2));

I used #overlord1234 function, but corrected ь: '', cuz English words don't have this letter, and next need return a[char] ?? char instead of return a[char] || char