56
votes
30
answers
2.2K
views
JavaScript closure inside loops – simple practical example
var funcs = []; // let's create 3 functions for (var i = 0; i < 3; i++) { // and store them in f
57
votes
30
answers
2K
views
Detecting an undefined object property
What's the best way of checking if an object property in JavaScript is undefined?
57
votes
30
answers
2.6K
views
How can I upload files asynchronously with jQuery?
I would like to upload a file asynchronously with jQuery. $(document).ready(function () { $("#uploa
56
votes
30
answers
2.3K
views
How can I change an element's class with JavaScript?
How can I change the class of an HTML element in response to an onclick or any other events using JavaScript?
50
votes
30
answers
1.9K
views
How can I check if an object is an array?
I'm trying to write a function that either accepts a list of strings, or a single string. If it's a
51
votes
14
answers
2.7K
views
event.preventDefault() vs. return false
When I want to prevent other event handlers from executing after a certain event is fired, I can use one of tw
63
votes
30
answers
1K
views
How do I loop through or enumerate a JavaScript object?
I have a JavaScript object like the following: var p = { "p1": "value1", "p2": "value2", "p3": "v
51
votes
25
answers
3.1K
views
What is the difference between call and apply?
What is the difference between using call and apply to invoke a function? var func = function() { alert(&ap
54
votes
25
answers
1.6K
views
Get the current URL with JavaScript?
All I want is to get the website URL. Not the URL as taken from a link. On the page loading I need to be able
71
votes
30
answers
2.9K
views
How to round to at most 2 decimal places, if necessary?
I'd like to round at most 2 decimal places, but only if necessary. Input: 10 1.7777777 9.1 Output: 1
52
votes
30
answers
1.1K
views
How can I check for an empty/undefined/null string in JavaScript?
I saw this question, but I didn't see a JavaScript specific example. Is there a simple string.Empty avail
60
votes
30
answers
600
views
Sort array of objects by string property value
I have an array of JavaScript objects: var objs = [ { first_nom: 'Lazslo', last_nom: 'Jam
53
votes
30
answers
1.5K
views
How do I correctly clone a JavaScript object?
I have an object x. I'd like to copy it as object y, such that changes to y do not modify x. I realized t
59
votes
25
answers
3K
views
Checking if a key exists in a JavaScript object?
How do I check if a particular key exists in a JavaScript object or array? If a key doesn't exist, and I
56
votes
20
answers
1.7K
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How to insert an item into an array at a specific index (JavaScript)
I am looking for a JavaScript array insert method, in the style of: arr.insert(index, item) Preferably in jQu
58
votes
30
answers
412
views
Loop through an array in JavaScript
In Java you can use a for loop to traverse objects in an array as follows: String[] myStringArray = {"Hello",
61
votes
30
answers
1.9K
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What is the !! (not not) operator in JavaScript?
I saw some code that seems to use an operator I don't recognize, in the form of two exclamation points, l
59
votes
30
answers
2.4K
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How do I copy to the clipboard in JavaScript?
What is the best way to copy text to the clipboard (multi-browser)? I have tried: function copyToClipboard(tex
65
votes
30
answers
1.1K
views
How do I test for an empty JavaScript object?
After an AJAX request, sometimes my application may return an empty object, like: var a = {}; How can I che
61
votes
30
answers
1.2K
views
Which "href" value should I use for JavaScript links, "#" or "javascript:void(0)"?
The following are two methods of building a link that has the sole purpose of running JavaScript code. Which i
