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JavaScript - replace last n items in array
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In this article, we would like to show you how to replace last n items in array using JavaScript.
Quick solution:
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const array = ['a', 'b', 'c', 'd'];2
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var replacements = ['x', 'y'];4
var n = replacements.length; // number of items to replace5
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array.splice(-n, n);7
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for (var i = 0; i < n; ++i) {9
array.push(replacements[i]);10
}11
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console.log(array); // ['a', 'b', 'x', 'y']or:
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let array = ['a', 'b', 'c', 'd'];2
let replacements = ['x', 'y'];3
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const n = replacements.length; // number of items to replace5
array.splice(-n, n);6
array = [array, replacements];7
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console.log(array); // ['a', 'b', 'x', 'y']
In this example, we create a reusable arrow function (modern JavaScript syntax) that can be used to replace n items in array.
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const replaceItems = (array, replacements) => {2
const n = replacements.length; // number of items to replace3
array.splice(-n, n);4
for (let i = 0; i < n; ++i) {5
array.push(replacements[i]);6
}7
return array;8
};9
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// Usage example:12
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const array = ['a', 'b', 'c', 'd'];14
const replacements = ['x', 'y'];15
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replaceItems(array, replacements);17
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console.log(array); // ['a', 'b', 'x', 'y']xxxxxxxxxx1
const replaceItems = (array, replacements) => {2
const n = replacements.length; // number of items to replace3
array.splice(-n, n);4
return [array, replacements];5
};6
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// Usage example:9
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const array = ['a', 'b', 'c', 'd'];11
const replacements = ['x', 'y'];12
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const result = replaceItems(array, replacements);14
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console.log(result); // ['a', 'b', 'x', 'y']
