How to use slice in js

slice is a JavaScript method used to extract a range of elements from an array or string. Syntax: array.slice(start, end), where start is the starting index (inclusive) and end is the ending index (inclusive). Usage methods include: extracting subarrays/substrings, copying arrays/strings, extracting elements from the beginning/end, and using the step parameter. The operation does not modify the original array and creates a new copy.

The slice method in JS

What is slice?

slice is a built-in method in JavaScript that is used to extract a range of elements from an array or string.

Syntax:

<code class="js">array.slice(start, end)</code>

Among them:

• start: The starting index of the extracted element (inclusive).
• end: The end index of the extracted element (exclusive).

Usage:

The slice method has the following usage:

• Extract a subarray or substring:

<code class="js">const arr = [1, 2, 3, 4, 5];
const subArr = arr.slice(1, 3); // [2, 3]

const str = "Hello World";
const subStr = str.slice(0, 4); // "Hell"</code>

• Copy an array or string:

By omitting the end parameter, slice can copy the entire array or character string.

<code class="js">const arrCopy = arr.slice();
const strCopy = str.slice();</code>

• Extract elements from the beginning or end:

Use negative indexes to extract elements from the beginning or end of an array or string.

<code class="js">const firstTwo = arr.slice(0, 2); // [1, 2]

const lastTwo = arr.slice(-2); // [4, 5]</code>

• Use the step parameter:

The third parameter step can specify the step size for element extraction. For example, a step of 2 means to extract only even-indexed elements from the array or string.

<code class="js">const evenIndices = arr.slice(0, arr.length, 2); // [1, 3, 5]</code>

Note:

The slice method does not modify the original array or string, but creates a new copy.

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