I've been told not to use for...in with arrays in JavaScript. Why not?...

How can I loop through all the entries in an array using JavaScript?  I thought it was something like this:  forEach(instance in theArray)   Where theArray is my array, but this seems to be incorrect....

In Java you can use a for loop to traverse objects in an array as follows:  String[] myStringArray = {"Hello", "World"}; for (String s : myStringArray) {     // Do something }   Can you do the same in JavaScript?...

var obj = {     name: "Simon",     age: "20",     clothing: {         style: "simple",         hipster: false     } }  for(var propt in obj){     console.log(propt + ': ' + obj[propt]); }     How does the variable...

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I'm working with a bit of html and Javascript code that I've taken over from someone else. The page reloads a table of data (via an asynchronous request) every ten seconds, and then re-builds the table using some DOM code. The code in quest...

I learned from books that you should write for loop like this?  for(var i=0, len=arr.length; i < len; i++){     // blah blah }   so the arr.length will not be calculated each time.    Others say that the compiler will do some optimization to thi...

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I've heard this quite a few times. Are JavaScript loops really faster when counting backward? If so, why? I've seen a few test suite examples showing that reversed loops are quicker, but I can't find any explanation as to why!  I'm...

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