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JavaScript - spread operator (...)
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In this article, we would like to show you how works spread operator in JavaScript.
The spread operator allows you to spread the iterated value into its components.
Usage examples:
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const array = [1, 2, 3, 4, 5];2
console.log(array); // 1, 2, 3, 4, 53
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// split the text into individual letters5
const string = "Dirask";6
console.log(string); // D, i, r, a, s, kxxxxxxxxxx1
const array = [1, 2, 3, 4, 5];2
const array2 = [array];3
console.log(array2); // 1, 2, 3, 4, 5xxxxxxxxxx1
const array1 = [2, 3, 4]2
const array2 = [1, array1, 5, 6, 7];3
console.log(array2); // 1, 2, 3, 4, 5, 6, 7Functions like Math.max() expect many parameters. We can't pass the array as one argument there, so we can use the spread operator.
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let array = [1, 2, 3, 4];2
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console.log(Math.max(1, 2, 3, 4)); // 44
console.log(Math.max(array)); // NaN5
console.log(Math.max(array)); // 46
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const object1 = {2
x : 5,3
y : 74
}5
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const object2 = {7
y : 11,8
z : 239
}10
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const object3 = {12
k: 33,13
object1,14
object215
};16
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const object3String = JSON.stringify(object3, null, 4);18
console.log(object3String); // { k : 33, x : 5, y : 11, z : 23 }As we can see above, the order does matter - y value from Object1 has been overridden by value from Object2.
Note:
There is also the
restoperator (...) which looks the same and works quite similar, but there are a few differences between thespreadoperator and therestoperator, which you can read about here.
