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slice vs splice

Written byPhuoc Nguyen
01 Aug, 2020
Last updated
07 Aug, 2020
`slice` and `splice` are common methods to get a sub-array of a given array.


  1. The signature of methods are different.
    array.slice(startingIndex, endingIndex);
    array.splice(startingIndex, length, ...items);
    While the first parameter are the same as each other indicating the starting index of removed elements, the second parameters aren't.
    The second parameter of `slice` and `splice` are the ending index and the number of sub items, respectively.
    With the `splice` method, it's possible to keep the items not to be removed from the original array by passing them to the last parameters.
  2. `splice` changes the original array, while `slice` doesn't.
    Given the array of numbers from 1 to 5:
    const array = [1, 2, 3, 4, 5];
    const sub = array.splice(2, 3);

    // The original array is modified
    array; // [1, 2]
    sub; // [3, 4, 5]
    Now, let's pass the same parameters to `slice`:
    const array = [1, 2, 3, 4, 5];
    const sub = array.slice(2, 3);

    // The original array isn't modified
    array; // [1, 2, 3, 4, 5]
    sub; // [3]


We can clone an array by ignoring the ending index:
const clone = (arr) => arr.slice(0);

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