Fastest way to duplicate an array in JavaScript - slice vs. 'for' loop

Question

In order to duplicate an array in JavaScript: which of the following is faster to use?

###Slice method

var dup_array = original_array.slice();
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Answer 1

        const arr = ['1', '2', '3'];

         // Old way
        const cloneArr = arr.slice();

        // ES6 way
        const cloneArrES6 = [...arr];

// But problem with 3rd approach is that if you are using muti-dimensional 
 // array, then only first level is copied

        const nums = [
              [1, 2], 
              [10],
         ];

        const cloneNums = [...nums];

// Let's change the first item in the first nested item in our cloned array.

        cloneNums[0][0] = '8';

        console.log(cloneNums);
           // [ [ '8', 2 ], [ 10 ], [ 300 ] ]

        // NOOooo, the original is also affected
        console.log(nums);
          // [ [ '8', 2 ], [ 10 ], [ 300 ] ]

So, in order to avoid these scenarios to happen, use

        const arr = ['1', '2', '3'];

        const cloneArr = Array.from(arr);