Dec 9, 2008 · The result of .push in the scenario will be = [ar1, [ar2]]. .concat solves that problem, but with sacrifice of speed and a new array created. To use .push properly in array appends, …

If your array of object is already empty, make sure it has at least one object, or that object in which you are going to push data to. Let's say, our array is myArray[], so this is now empty …

The ".apply" has to check each index in the array and convert it to a set of arguments before passing it to Array.prototype.push. Then, Array.prototype.push has to additionally allocate …

Feb 25, 2009 · So in this way we can return a new array (will be a cool functional way - more much better than using push or splice) with the element inserted at index, and if the index is …

He wants to push to existing array so Array.prototype.push.apply(arr1, arr2) is the correct answer, because using arr1.concat(arr2) you are creating a new array. – suricactus Commented Aug …

Actually, all unshift/push and shift/pop mutate the source array. The unshift/push add an item to the existed array from begin/end and shift/pop remove an item from the beginning/end of an …

Apr 19, 2016 · so not sure if this answers your question but the indexOf the items you are adding keep returning -1. Not to familiar with js but it appears the items do that because they are not …

Jul 21, 2011 · Best thing with concat is it will return a reference to the resulting array. So it's perfect to use it in functional programming and chaining. Array.prototype.concat() is my …

Jun 15, 2017 · The push() adds elements to the end of an array and returns the new length of the array. Thus your return here is invalid. The concat() method is used to merge arrays. Concat …

Use .unshift() to add to the beginning of an array. TheArray.unshift(TheNewObject); See MDN for doc on unshift() and here for doc on other array methods. FYI, just like there's .push() and …