I have an array in javascript and a variable as follows:
var numArr = ["one", "two", "three"];
var searchNum = "four";
I want to search "four" in numArr and if not present then execute some statements... as in
if (searchNum not in numArr)
{
// do this
}
Does javascript have any function which could search in any array and return true or false without me writing a whole lot of search code.
Use indexOf:
if ( numArr.indexOf(searchNum) > -1 ) {
} else {}
The method will return -1 if it fails to find searchNum. Otherwise it will return the index at which it found it.
You can also use:
var result = [];
for(i=0;i<listdata.names.length;i++){
var n = listdata.names[i].toLocaleLowerCase();
var s = x('input').value.toLocaleLowerCase();
if(n.indexOf(s) != -1){result.push(listdata.names[i]);}
}
This way we can output an result from an input value and existing array of values.
Little typicall to understand but..... :)
Related
I am trying to filter some data from an array in a JSON file, based on an input of the form string1, string1,string2, string1,string2,string3 etc., that is, some strings separated by a ,.
What I'm trying to do:
let arrInput = document.getElementById('inputBox').val.split(',');
for(let i = 0; i < arrToFilter.length; i++){
if(.........what to write here?...........){
arrOutput.push(arrToFilter[i]);
}
}
return arrOutput;
If the arrInput had a fixed length, I could accomplish this using indexOf != -1 for each element in arrInput, but here, since the length of arrInput is variable, how can I check if at least one of the strings present in arrInput is also present as a substring in arrToFIlter[i]?
Edit:
Example:
Let arrToFilter be ["abcqwer", "pizza", "definition", "abcdef", "example"]
Case 1 :
Say the input entered (in an <input> element) is abc,def.
For this, the arrOutput should be ["abcqwer", "definition", "abcdef"]
Case 2:
Say the input entered is abc
Expected output : ["abcqwer", "abcdef"]
Simple way is using some and filter,
var string = 'ad,kk,sb';
var array = ['adik', 'klop', 'pp'];
var stringers = string.split(',');
var result = array.filter((arr) => {
var isPresent = stringers.some(stringer => arr.includes(stringer));
return isPresent ? true : false;
});
console.log(result);
You need to iterate both arrays
let arrToFilter = ['abcqwer', 'pizza', 'definition', 'abcdef', 'example'];
let arrOutput = [];
let arrInput = document.getElementById('inputBox').value.split(',');
arrToFilter.forEach(filter => {
arrInput.forEach(input => {
if (!!input && filter.includes(input)) {
arrOutput.push(filter);
}
});
});
// distinct the output
return arrOutput.filter((v, i, a) => i === a.indexOf(v));
I have an array of strings like thisvar arr = ['BUTTON','BADGE','CHECKBOX]'
Now I need a if condition to be written for the strings except those present in the array. How do I do that??
I'm a beginner and know nothing much about javascript. Thanks in advance for your help.
I tried var arr = ['BUTTON','BADGE','CHECKBOX];
if(!arr){
//code to be executed
}
However this always returns false.
You can use indexOf:
if(arr.indexOf(test_variable) === -1){
// element doesn't exist in array
}
I don't really understand your question but maybe array.some can solve your problem:
var someString = 'BADGE';
var arr = ['BUTTON','BADGE','CHECKBOX' ];
if (arr.some(str => str === someString)) {
console.log("Exist");
} else {
console.log("Doesn't exist");
}
This is how to do it:
var pippo = "pippo";
var arr = ['BUTTON','BADGE','CHECKBOX'];
if(arr.indexOf(pippo) > -1){
console.log("contained!");
}
else{
console.log("not contained!");
}
First of all the last element of your array/list is not properly written as a string i.e 'CHECKBOX. You missed a single quote in the end so it should be 'CHECKBOX'
var arr = ['BUTTON','BADGE','CHECKBOX];
↓
var arr = ['BUTTON','BADGE','CHECKBOX'];
Secondly coming to your actual query, according to your question it seems you want to run a piece of code if a string is not present in the array.
For this, you can use the array.indexOf() function which returns the position/index of the variable in the array passed as a parameter to it & if the variable is not present in the array, it returns a value of -1
More about this:- https://www.w3schools.com/jsref/jsref_indexof_array.asp
So the code for that would be:-
var arr = ['BUTTON','BADGE','CHECKBOX'];
var str = 'foo'; //string not present in the array i.e arr
if(arr.indexOf(str) === -1) {
//your code here
}
length will works for you if comes 0, return 0 when not element exists in the arrayset
var arr = ['BUTTON','BADGE','CHECKBOX'];
console.log(arr.length)
So I'm a little stuck as to why this isn't working. I'm trying to remove all of the empty strings in an array and it keeps giving me back an array that is just one empty string. Any ideas?
function splitNames(){
var names = document.getElementById("1").value.split("\n");
for(var i = 0; i<=names.length; i++){
if(names[i]==""){
names = names.splice(i, 1);
console.log(names);
}
}
console.log(names);
}
The string would look like this by the way.
Hi
Hello
(remove this one)
Bonjour
blah
(remove this one)
(remove this one)
blah
The array comes out to this ["Hi", "Hello","",...]
Perhaps the simplest way to do this is to use the filter function and search for truthy values. By default, empty strings are false.
The filter() method creates a new array with all elements that pass the test implemented by the provided function.
var strings = ["zebras", "trees", "forests", "", "hi", "wizards", "", "", "lizards"];
strings = strings.filter((e) => e);
console.log(strings);
It's important to note that empty strings by default are false. However, strings that contain only whitespace characters are true. In that scenario, my example would not work and you would have to do this
strings.filter((e) => e.trim());
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter
function splitNames(){
// var names = document.getElementById("1").value.split("\n");
var names = "Hi\nHello\n \nGoodBye".split("\n");
var filteredNames = names.filter(function(item){
return item.trim() !== "";
});//filter
return filteredNames;
}//splitNames()
console.log( splitNames() );
Create a new array and push what you need.
function splitNames(){
var names = document.getElementById("1").value.split("\n");
var newArr = [];
for(var i = 0; i<=names.length; i++){
if(names[i]){
newArr.push(names[i]);
}
}
return newArr.join('\n');
//console.log(names);
}
try it:
function splitNames(){
var names = document.getElementById("1").value.split("\n");
var newArr = names.filter(function(name){
return name!=="";
});
return newArr;
}
I found a lot of related questions with answers talking about for...in loops and using hasOwnProperty but nothing I do works properly. All I want to do is check whether or not a key exists in an array and if not, add it.
I start with an empty array then add keys as the page is scrubbed with jQuery.
Initially, I hoped that something simple like the following would work: (using generic names)
if (!array[key])
array[key] = value;
No go. Followed it up with:
for (var in array) {
if (!array.hasOwnProperty(var))
array[key] = value;
}
Also tried:
if (array.hasOwnProperty(key) == false)
array[key] = value;
None of this has worked. Either nothing is pushed to the array or what I try is no better than simply declaring array[key] = value Why is something so simple so difficult to do. Any ideas to make this work?
Generally speaking, this is better accomplished with an object instead since JavaScript doesn't really have associative arrays:
var foo = { bar: 0 };
Then use in to check for a key:
if ( !( 'bar' in foo ) ) {
foo['bar'] = 42;
}
As was rightly pointed out in the comments below, this method is useful only when your keys will be strings, or items that can be represented as strings (such as numbers).
var a = [1,2,3], b = [4,1,5,2];
b.forEach(function(value){
if (a.indexOf(value)==-1) a.push(value);
});
console.log(a);
// [1, 2, 3, 4, 5]
For more details read up on Array.indexOf.
If you want to rely on jQuery, instead use jQuery.inArray:
$.each(b,function(value){
if ($.inArray(value,a)==-1) a.push(value);
});
If all your values are simply and uniquely representable as strings, however, you should use an Object instead of an Array, for a potentially massive speed increase (as described in the answer by #JonathanSampson).
A better alternative is provided in ES6 using Sets. So, instead of declaring Arrays, it is recommended to use Sets if you need to have an array that shouldn't add duplicates.
var array = new Set();
array.add(1);
array.add(2);
array.add(3);
console.log(array);
// Prints: Set(3) {1, 2, 3}
array.add(2); // does not add any new element
console.log(array);
// Still Prints: Set(3) {1, 2, 3}
If you're already using spread...
let colors = ['red', 'orange', 'yellow'];
let moreColors = ['orange', 'green'];
let mergedColors = [...colors, ...moreColors];
and want to avoid duplicates...
let mergedColors = [...colors, ...moreColors.filter(c => !colors.includes(c)) ];
You can try this:
var names = ["Mike","Matt","Nancy","Adam","Jenny","Nancy","Carl"];
var uniqueNames = [];
$.each(names, function(i, el){
if($.inArray(el, uniqueNames) === -1) uniqueNames.push(el);
});
Easiest way to find duplicate values in a JavaScript array
The logic is wrong. Consider this:
x = ["a","b","c"]
x[0] // "a"
x["0"] // "a"
0 in x // true
"0" in x // true
x.hasOwnProperty(0) // true
x.hasOwnProperty("0") // true
There is no reason to loop to check for key (or indices for arrays) existence. Now, values are a different story...
Happy coding
function check (list){
var foundRepeatingValue = false;
var newList = [];
for(i=0;i<list.length;i++){
var thisValue = list[i];
if(i>0){
if(newList.indexOf(thisValue)>-1){
foundRepeatingValue = true;
console.log("getting repeated");
return true;
}
} newList.push(thisValue);
} return false;
}
var list1 = ["dse","dfg","dse"];
check(list1);
Output:
getting repeated
true
let x = "farceus";
let y = "character";
const commonCharacters = function (string1, string2) {
let duplicateCharacter = "";
for (let i = 0; i < string1.length; i += 1) {
if (duplicateCharacter.indexOf(string1[i]) === -1) {
if (string2.indexOf(string1[i]) !== -1) {
duplicateCharacter += string1[i];
}
}
}
return [...duplicateCharacter];
};
console.log(commonCharacters(x, y));
Solving another array manipulation, and I'm taking longer than usual to solve this. I need help in combining array values:
var array1 = ["alpha|LJ", "bravo|MH", "charlie|MH", "delta|MF",
"echo|16", "{foxtrot}|GG", "{golf}|HS"];
var array2 = ["charlie-{golf}-{foxtrot}", "echo-{golf}"]; //some templates
such that the final array be:
final_array = ["alpha-LJ", "bravo-MH", "charlie-HS-GG-MH", "delta-MF",
"echo-HS-16"];
To make it clear how I arrived with the final_array, alpha, bravo and delta only got their "|" replaced with "-" since they are not found on my array2 template. charlie and echo got the template so the respective values of the {} were replaced based on array1. Array1 honestly is not the best key:value relationship that I could come up for now.
Here are some requirementL:
* Anything in array1 with {} braces are not meant to be templated.
* Keywords in array2 will always have a matching value in array1.
I've read about jquery .map() and thinking that it is achievable using this, maybe together with Regexp. Hope you'll utilize these. Also, if it helps, final_array can be of any order.
I really need to up my knowledge on these two topics... :|
Thank you in advance.
Edit: Updated to match your output and comment some of the madness. This doesn't feel like it's the most efficient, given the split() done to values at the start and then again at the end...but it works.
function funkyTransform( values, templates ){
// Make a copy of the array we were given so we can mutate it
// without rudely changing something passed to our function.
var result = values.concat();
// Map {value} entries for later lookup, and throw them out of the result
var valueMap = {};
for (var i=result.length-1;i>=0;--i){
var pair = result[i].split('|');
if (pair[0][0]=="{"){
valueMap[pair[0]] = pair[1];
result.splice(i,1); // Yank this from the result
}
}
console.log(valueMap);
// {
// "{foxtrot}": "GG",
// "{golf}": "HS"
// }
// Use the value map to replace text in our "templates", and
// create a map from the first part of the template to the rest.
// THIS SHOULD REALLY SCAN THE TEMPLATE FOR "{...}" PIECES
// AND LOOK THEM UP IN THE MAP; OOPS O(N^2)
var templateMap = {};
for (var i=templates.length-1;i>=0;--i){
var template = templates[i];
for (var name in valueMap){
if (valueMap.hasOwnProperty(name)){
template = template.replace(name,valueMap[name]);
}
}
var templateName = template.split('-')[0];
templateMap[ templateName ] = template.slice(templateName.length+1);
}
console.log(templateMap);
// {
// "charlie": "HS-GG",
// "echo": "HS"
// }
// Go through the results again, replacing template text from the templateMap
for (var i=result.length-1;i>=0;--i){
var pieces = result[i].split('|');
var template = templateMap[pieces[0]];
if (template) pieces.splice(1,0,template);
result[i] = pieces.join('-');
}
return result;
}
var output = funkyTransform( array1, array2 );
console.log(output);
// ["alpha-LJ", "bravo-MH", "charlie-HS-GG-MH", "delta-MF", "echo-HS-16"]
This managed to get your desired output, though I made a few assumptions:
Anything in array1 with {} braces are not meant to be templated.
Keywords in array2 will always have a matching value in array1 (this can easily be changed, but not sure what your rule would be).
Code:
// This is the main code
var final_array = $.map(array1, function (item) {
var components = item.split('|');
// Ignore elements between {} braces
if (/^\{.*\}$/.test(components[0])) return;
components[0] = template(components[0]);
return components.join('-');
});
// Helper to lookup array2 for a particular string and template it
// with the values from array1
function template(str) {
var index = indexOfMatching(array2, str, '-');
if (index == -1) return str;
var components = array2[index].split('-');
var result = [str];
for (var i = 1; i < components.length; i++) {
result.push(array1[indexOfMatching(array1, components[i], '|')]
.split('|')[1]);
}
return result.join('-');
}
// Helper to for looking up array1 and array2
function indexOfMatching(array, target, separator) {
for (var i = 0; i < array.length; i++) {
if (array[i].split(separator)[0] === target) return i;
}
return -1;
}