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I want to replace elements in some array from 0 element, with elements of another array with variable length. Like:
var arr = new Array(10), anotherArr = [1, 2, 3], result; result = anotherArr.concat(arr); result.splice(10, anotherArr.length); Is there some better way?
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splice() method can be used to add, remove, and replace elements from an array. This method modifies the contents of the original array by removing or replacing existing elements and/or adding new elements in place. Array. splice() returns the removed elements (if any) as an array.
The method arr. concat creates a new array that includes values from other arrays and additional items. It accepts any number of arguments – either arrays or values.
You can use the splice method to replace part of an array with items from another array, but you have to call it in a special way as it expects the items as parameters, not the array.
The splice method expects parameters like (0, anotherArr.Length, 1, 2, 3), so you need to create an array with the parameters and use the apply method to call the splice method with the parameters:
Array.prototype.splice.apply(arr, [0, anotherArr.length].concat(anotherArr)); Example:
var arr = [ 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j']; var anotherArr = [ 1, 2, 3 ]; Array.prototype.splice.apply(arr, [0, anotherArr.length].concat(anotherArr)); console.log(arr); Output:
[ 1, 2, 3, 'd', 'e', 'f', 'g', 'h', 'i', 'j'] Demo: http://jsfiddle.net/Guffa/bB7Ey/
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