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JavaScript : Array assignment creates reference not copy
Consider we have an array var a = [1,2,3,4]; and we assign var b = a; then b not a copy of a, b is a pointer to a. So if you make any changes on b will have effect on a as well. Here is an example.
var a = [1,2,3,4]; var b = a; var b.pop(); console.log(b); // [1, 2, 3] console.log(a); // [1, 2, 3] so if you really want a copy of a you need to use .slice method.
var a = [1,2,3,4]; var b = a.slice(0); var b.pop(); console.log(b); // [1, 2, 3] console.log(a); // [1, 2, 3, 4] JavaScript doesn’t have a clone method for array, so if you really want, you can define yourself on Array but its not highly recommended.
Array.prototype.clone = function(){ return this.slice(0) } Now you can call .clone on any Array type.
var a = [1,2,3,4]; var b = a.clone(); var b.pop(); console.log(b); // [1, 2, 3] console.log(a); // [1, 2, 3, 4] I recommend to keep this in mind when ever you are dealing with JavaScript Array’s, else you might facing some unexpected behaviour and wonder why it happens.
Happy coding.
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