If we want to make a copy of an array in JavaScript, we can use Array#slice method. This way we will get a copy of the array. If we are simply assigning the array to another variable, it is not making a copy. So performing splice() operation on the array will affect the value stored in both variables.

var a = [1,2,3],
    b = a;
a.splice(1,1); // => a is [1,3] and b is also [1,3]

var a = [1,2,3],
    b = a.slice(0);
a.splice(1,1); // => a is [1,3] and b is [1,2,3]