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How to Empty an Array? The Allocation Way
The first answer that I occasionally see is to allocate a new array:
var a = [1, 2, 3]; // later in code a = ;
While this method will empty the array, it might lead to reference problems. A reference problem will happen if you have another reference to the original array. For example:
var a = [1, 2, 3], b = a; // later in code a = ; console.log(b); // will print [1, 2, 3]
In the previous code we thought that we emptied both a and b arrays but it might lead to an error later because the b array didn’t get empty.
How to Empty an Array? My Preferred Solution
var a = [1, 2, 3]; // later in code a.length = 0
By setting the array length to 0 you empty an array and you won’t allocate a new array in the process. This method will also help you avoiding reference problems like the one I showed earlier:
var a = [1, 2, 3], b = a; // later in code a.length = 0; console.log(b); // will print 
Here the console will print an empty array both for a and b arrays.
If you want to see the performance implications of using one of this methods you can go to the this linkwhich include a benchmark that check both of these methods in various of browsers.