As of JULY 2018, this has been implemented in almost all major browsers, if you need to support an older browser a polyfill is available. Edit: Note that this returns false if the item in the array is an object. This is because similar objects are two different objects in JavaScript.

Jun 10, 2010 · In the case of an array, the callback is passed an array index and a corresponding array value each time. (The value can also be accessed through the this keyword, but Javascript will always wrap the this value as an Object even if it is a simple string or number value.)

Feb 17, 2012 · JavaScript has powerful semantics for looping through arrays and array-like objects. I've split the answer into two parts: Options for genuine arrays, and options for things that are just array- like, such as the arguments object, other iterable objects (ES2015+), DOM collections, and so on. Okay, let's look at our options: For Actual Arrays

Aug 28, 2017 · The filter () method creates a new array with all elements that pass the test implemented by the provided function. Also, use typeof operator in order to find out the type of item from array.

Aug 5, 2009 · This will clear the existing array by setting its length to 0. It also works when using "strict mode" in ECMAScript 5 because the length property of an array is a read/write property. Method 3 (as suggested by Anthony)

Oct 21, 2011 · How can I retrieve a column from a 2-dimensional array and not a single entry? I'm doing this because I want to search for a string in one of the columns only so if there is another way to accomplish

Oct 25, 2013 · Learn how to extract values from an array of objects using JavaScript.

May 22, 2013 · Could somebody please help me to create an array of array.I have a matrix calculator and I want to create an array of arrays ('smaller').How can I do it?The functiions create2Darray and calculateDe...

May 1, 2013 · Use a for loop and iterate over the target array. If every element is contained within the current array (use current.indexOf(elem) !== -1), then they're all in there.

testvar [1] is the value of that array index, which is the number 2. Numbers don't have a length property, and you're checking for 2.length which is undefined. If you want the length of the array just check testvar.length