I have the following code:
var fl = myitems(); //grabs all items (an array)
var f1 = f2 = new String();
function myfunc(){
//find two items in an array and load vars
for(i=0; i<fl.length-1; i++){
if(fl[i] == "match1"){
f1 = fl[i];
}
}
for(i=0; i<fl.length-1; i++){
if(fl[i] == "match2"){
f2 = fl[i];
}
}
}
I'd like to avoid the extra for(), if possible. I try else if, but many times the first match element is caught after the 2nd element has already been surpassed in the for loop.
I'm sure there is an easy way out of this (else if, and else don't seem to do the trick).
Can anyone tell me what common practice is here?
You can do both tests in the same loop:
for (i = 0; i < fl.length - 1; i++) {
if (fl[i] == "match1") {
f1 = fl[i];
} else if (fl[i] == "match2") {
f2 = fl[i];
}
}
Note that the comparison operator is ==, not =.
I know that this does not answer the original question, but it looks like you are trying to find out whether the arrays contain 'match1' and 'match2', you can do that with Array.prototype.indexOf:
var items = myitems();
if(items.indexOf('match1') !== -1) {
// Do whatever you need to do if the array contains 'match1'
}
Related
I'm trying to compare the variable determineHour against the array stationRentalsHours, whenever the variable would be equal to a stationRentalsHours element, I'd like to add that element to another Array (stationRentalsHoursTemp), but only the values that match. I tried with simple operators, but that doesn't put anything into the temp array. I also tried using JQuery $.inArray, but that gives me some strange results, Equal to those in the original array. Are there any other methods of comparing a variable with an array for this particular task?
Thank you for any help.
function updateChart() {
if(canvas3){canvas3.destroy();}
var determineHour = selectNumber.options[selectNumber.selectedIndex].innerHTML;
for (var i = 0; i < stationRentalsHours.length; i++) {
/*if(determineHour == stationRentalsHours){
stationRentalsHoursTemp.push(stationRentalsHours[i]);*/
if( $.inArray(determineHour, stationRentalsHours[i])){
stationRentalsHoursTemp.push(stationRentalsHours[i]);
}
}
In this case, instead of using $.inArray, you can simply use the for loop and the index to test the equality. I guess you mixed up two things:
var determineHour = selectNumber.options[selectNumber.selectedIndex].innerHTML;
for (var i = 0; i < stationRentalsHours.length; i++) {
if( determineHour == stationRentalsHours[i]){
stationRentalsHoursTemp.push(stationRentalsHours[i]);
}
}
Better yet, use filter:
var determineHour = selectNumber.options[selectNumber.selectedIndex].innerHTML;
stationRentalsHoursTemp = stationRentalsHours.filter(function(val){return val == determineHour;});
Instead of
if( $.inArray(determineHour, stationRentalsHours[i])){
Try
if( $.inArray(determineHour, stationRentalsHours) != -1){
Your commented out code would do the trick with a slight amendment to the if condition. Your original condition was comparing a string to an array instead of an individual element in that array:
function updateChart() {
if(canvas3){
canvas3.destroy();
}
var determineHour = selectNumber.options[selectNumber.selectedIndex].innerHTML;
for (var i = 0; i < stationRentalsHours.length; i++){
if(determineHour == stationRentalsHours[i]){
stationRentalsHoursTemp.push(stationRentalsHours[i]);
}
}
}
I have an array of characters like this:
['a','b','c','d','f']
['O','Q','R','S']
If we see that, there is one letter is missing from each of the arrays. First one has e missing and the second one has P missing. Care to be taken for the case of the character as well. So, if I have a huge Object which has all the letters in order, and check them for the next ones, and compare?
I am totally confused on what approach to follow! This is what I have got till now:
var chars = ("abcdefghijklmnopqrstuvwxyz"+"abcdefghijklmnopqrstuvwxyz".toUpperCase()).split("");
So this gives me with:
["a","b","c","d","e","f","g","h","i","j","k","l","m",
"n","o","p","q","r","s","t","u","v","w","x","y","z",
"A","B","C","D","E","F","G","H","I","J","K","L","M",
"N","O","P","Q","R","S","T","U","V","W","X","Y","Z"]
Which is awesome. Now my question is, how do I like check for the missing character in the range? Some kind of forward lookup?
I tried something like this:
Find the indexOf starting value in the source array.
Compare it with each of them.
If the comparison failed, return the one from the original array?
I think that a much better way is to check for each element in your array if the next element is the next char:
function checkMissingChar(ar) {
for (var i = 1; i < ar.length; i++) {
if (ar[i].charCodeAt(0) == ar[i-1].charCodeAt(0)+1) {
// console.log('all good');
} else {
return String.fromCharCode(ar[i-1].charCodeAt(0)+1);
}
}
return true;
}
var a = ['a','b','c','d','f']
var b = ['O','Q','R','S']
console.log(checkMissingChar(a));
console.log(checkMissingChar(b));
Not that I start to check the array with the second item because I compare it to the item before (the first in the Array).
Forward Look-Ahead or Negative Look-Ahead: Well, my solution would be some kind of that. So, if you see this, what I would do is, I'll keep track of them using the Character's Code using charCodeAt, instead of the array.
function findMissingLetter(array) {
var ords = array.map(function (v) {
return v.charCodeAt(0);
});
var prevOrd = "p";
for (var i = 0; i < ords.length; i++) {
if (prevOrd == "p") {
prevOrd = ords[i];
continue;
}
if (prevOrd + 1 != ords[i]) {
return String.fromCharCode(ords[i] - 1);
}
prevOrd = ords[i];
}
}
console.log(findMissingLetter(['a','b','c','d','f']));
console.log(findMissingLetter(['O','Q','R','S']));
Since I come from a PHP background, I use some PHP related terms like ordinal, etc. In PHP, you can get the charCode using the ord().
As Dekel's answer is better than mine, I'll try to propose somewhat more better answer:
function findMissingLetter (ar) {
for (var i = 1; i < ar.length; i++) {
if (ar[i].charCodeAt(0) != ar[i-1].charCodeAt(0)+1) {
return String.fromCharCode(ar[i-1].charCodeAt(0)+1);
}
}
return true;
}
var a = ['a','b','c','d','f']
var b = ['O','Q','R','S']
console.log(findMissingLetter(a));
console.log(findMissingLetter(b));
Shorter and Sweet.
I'm just studying JS and I need to write a program that checkes if the string in the first element of the array contains all of the letters of the string in the second element of the array.
I've made a code like this:
function mutation(arr) {mutation: {
var lowerCaseStringOne = arr[0].toLowerCase();
var lowerCaseStringTwo = arr[1].toLowerCase();
if (lowerCaseStringOne === lowerCaseStringTwo) {
console.log(true);
break mutation;
}
var newArray = [];
for (var i = 0; i < lowerCaseStringTwo.length; i++){
console.log(lowerCaseStringTwo[i]);
if (lowerCaseStringTwo.indexOf(lowerCaseStringOne[i]) > 0) {
newArray.push(lowerCaseStringTwo[i]);
console.log('---');
}
}
var result = newArray.join("");
if (result === lowerCaseStringTwo) {
console.log(true);
} else {
console.log(false);
}
}
}
mutation(["Mary", "Aarmy"]);
I think it's very complicated, but I can't solve the problem - the "indexOf" function seems to ignore a second character in my loop - loggs it in the console but doesn't pushes into an array. I thought it could happen because first and second letters are similar, but it's not. No matter what letter, it just ignores it.
indexOf() will return 0 for the letter "a" in your example as the first instance is at position 0 in the array.
You should be using ">= 0"
I'm very new to JS so go easy on me. I've got this array inside a variable, and am trying to find a better way to write that if statement. So if the names inside that variable grow, I won't need to change the if statement as it won't be hardcoded.
var names = ["beth", "barry", "debbie", "peter"]
if (names[0] && names [1] && names [2] && names [3] {
Do something...
}
Something tells me I need to be using the .length property but I can't work out how to properly use it within that statement. Something along the lines of:
if (names[i] * names.length) {
Do something...
}
I know that's wrong. I think need to be finding the index of each and looping through it makign sure it the loop doesn't exceed the amount of values in the array.
Any help is appreciated. Thanks in advance!
Update: Some users have alerted me that my question might not be as clear. I've setup a CodePen here (http://codepen.io/realph/pen/KjCLd?editors=101) that might explain what I'm trying to achieve.
P.S. How do I stop my from repeating 3 times?
You can use every to test whether every element satisfies some condition:
if (names.every(function (name) { return name })) {
// Do Something
}
every will automatically stop testing when the first non-true element is found, which is potentially a large optimization depending on the size of your array.
Traditionally, you would simply iterate over the array and test each element. You can do so with forEach or a simple for loop. You can perform the same early-termination when you find a non-true element by returning false from the forEach callback.
var allTrue = true;
names.forEach(function (name) {
return allTrue = allTrue && name;
});
if (allTrue) {
// Do something...
}
Please give a english description of what you are trying to accomplish. The below answer assumes you simply want to iterate a list of names and do some processing with each.
You want to use a for loop.
var names = ["beth", "barry", "debbie", "peter"]
for (var i=0; i<names.length; i++) {
// access names[i]
}
The best cross-browser solution is to use a traditional for loop.
var names = ["beth", "barry", "debbie", "peter"],
isValid = true,
i;
for (i = 0; i < names.length; i++) {
isValid = isValid && names[i];
}
if (isValid) {
// do something
}
You can try this;
var checkCondition = true;
for(var i = 0; i<names.length; i++){
if(names[i] !== something) {
checkCondition = false;
break;
}
}
if(checkCondition){
//Do what ever you like if the condition holds
}else{
// Do whatever you like if the condition does NOT holds
}
If i understand right you need something like this
var names = ["beth", "barry", "debbie", "peter"];
var notUndefinedNames = names.filter(function(el){return el !== undefined;});
// if all
if (names.length === notUndefinedNames.length) console.log("You're all here. Great! Sit down and let's begin the class.");
// if one or less
else if (notUndefinedNames.length <= 1) console.log("I can't teach just one person. Class is cancelled.");
else console.log("Welcome " + notUndefinedNames.join(', '));
I've got an in page text search using JS, which is here:
$.fn.eoTextSearch = function(pat) {
var out = []
var textNodes = function(n) {
if (!window['Node']) {
window.Node = new Object();
Node.ELEMENT_NODE = 1;
Node.ATTRIBUTE_NODE = 2;
Node.TEXT_NODE = 3;
Node.CDATA_SECTION_NODE = 4;
Node.ENTITY_REFERENCE_NODE = 5;
Node.ENTITY_NODE = 6;
Node.PROCESSING_INSTRUCTION_NODE = 7;
Node.COMMENT_NODE = 8;
Node.DOCUMENT_NODE = 9;
Node.DOCUMENT_TYPE_NODE = 10;
Node.DOCUMENT_FRAGMENT_NODE = 11;
Node.NOTATION_NODE = 12;
}
if (n.nodeType == Node.TEXT_NODE) {
var t = typeof pat == 'string' ?
n.nodeValue.indexOf(pat) != -1 :
pat.test(n.nodeValue);
if (t) {
out.push(n.parentNode)
}
}
else {
$.each(n.childNodes, function(a, b) {
textNodes(b)
})
}
}
this.each(function() {
textNodes(this)
})
return out
};
And I've got the ability to hide columns and rows in a table. When I submit a search and get the highlighted results, there would be in this case, the array length of the text nodes found would be 6, but there would only be 3 highlighted on the page. When you output the array to the console you get this:
So you get the 3 tags which I was expecting, but you see that the array is actually consisting of a [span,undefined,span,undefined,undefined,span]. Thus giving me the length of 6.
<span>
<span>
<span>
[span, undefined, span, undefined, undefined, span]
I don't know why it's not stripping out all of the undefined text nodes when I do the check for them. Here's what I've got for the function.
performTextSearch = function(currentObj){
if($.trim(currentObj.val()).length > 0){
var n = $("body").eoTextSearch($.trim(currentObj.val())),
recordTitle = "matches",
arrayRecheck = new Array(),
genericElemArray = new Array()
if(n.length == 1){
recordTitle = "match"
}
//check to see if we need to do a recount on the array length.
//if it's more than 0, then they're doing a compare and we need to strip out all of the text nodes that don't have a visible parent.
if($(".rows:checked").length > 0){
$.each(n,function(i,currElem){
if($(currElem).length != 0 && typeof currElem != 'undefined'){
if($(currElem).closest("tr").is(":visible") || $(currElem).is(":visible")){
//remove the element from the array
console.log(currElem)
arrayRecheck[i] = currElem
}
}
})
}
if(arrayRecheck.length > 0){
genericElemArray.push(arrayRecheck)
console.log(arrayRecheck)
}
else{
genericElemArray.push(n)
}
genericElemArray = genericElemArray[0]
$("#recordCount").text(genericElemArray.length + " " +recordTitle)
$(".searchResults").show()
for(var i = 0; i < genericElemArray.length; ++i){
void($(genericElemArray[i]).addClass("yellowBkgd").addClass("highLighted"))
}
}
else{
$(".highLighted").css("background","none")
}
}
If you look at the code below "//check to see if we need to do a recount on the array length. ", you'll see where I'm stripping out the text nodes based off of the display and whether or not the object is defined. I'm checking the length instead of undefined because the typeof == undefined wasn't working at all for some reason. Apparently, things are still slipping by though.
Any idea why I'm still getting undefined objects in the array?
My apologies for such a big post!
Thanks in advance
I've modified your eoTextSearch() function to remove dependencies on global variables in exchange for closures:
$.fn.extend({
// helper function
// recurses into a DOM object and calls a custom function for every descendant
eachDescendant: function (callback) {
for (var i=0, j=this.length; i<j; i++) {
callback.call(this[i]);
$.fn.eachDescendant.call(this[i].childNodes, callback);
}
return this;
},
// your text search function, revised
eoTextSearch: function () {
var text = document.createTextNode("test").textContent
? "textContent" : "innerText";
// the "matches" function uses an out param instead of a return value
var matches = function (pat, outArray) {
var isRe = typeof pat.test == "function";
return function() {
if (this.nodeType != 3) return; // ...text nodes only
if (isRe && pat.test(this[text]) || this[text].indexOf(pat) > -1) {
outArray.push(this.parentNode);
}
}
};
// this is the function that will *actually* become eoTextSearch()
return function (stringOrPattern) {
var result = $(); // start with an empty jQuery object
this.eachDescendant( matches(stringOrPattern, result) );
return result;
}
}() // <- instant calling is important here
});
And then you can do something like this:
$("body").eoTextSearch("foo").filter(function () {
return $(this).closest("tr").is(":visible");
});
To remove unwanted elements from the search result. No "recounting the array length" necessary. Or you use each() directly and decide within what to do.
I cannot entirely get my head around your code, but the most likely issue is that you are removing items from the array, but not shrinking the array afterwards. Simply removing items will return you "undefined", and will not collapse the array.
I would suggest that you do one of the following:
Copy the array to a new array, but only copying those items that are not undefined
Only use those array items that are not undefined.
I hope this is something of a help.
Found the answer in another post.
Remove empty elements from an array in Javascript
Ended up using the answer's second option and it worked alright.