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What do three dots mean in vue

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Release: 2024-05-02 22:24:50
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The three dots (...) in Vue represent the spread operator, which is used to: expand arrays and merge multiple array elements into a new array. Expand objects to combine the properties and values ​​of multiple objects into a new object. Expand function parameters to receive an indefinite number of parameters.

What do three dots mean in vue

The meaning of three dots (...) in Vue

In Vue, three dots ( ...) represents the expansion operator, which has the following effects:

Expand array

<code>const arr1 = [1, 2, 3];
const arr2 = [4, 5];
const combinedArr = [...arr1, ...arr2]; // [1, 2, 3, 4, 5]</code>
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Expand object

<code>const obj1 = { name: 'John', age: 30 };
const obj2 = { city: 'New York' };
const combinedObj = { ...obj1, ...obj2 }; // { name: 'John', age: 30, city: 'New York' }</code>
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Expand function parameters

<code>const sum = (...numbers) => {
  let total = 0;
  for (const number of numbers) {
    total += number;
  }
  return total;
};
console.log(sum(1, 2, 3, 4, 5)); // 15</code>
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Other uses

  • ##Clone an array or object: Combine the spread operator with Object.assign() enables fast cloning.
  • Filter array: Used in conjunction with Array.prototype.filter() to filter elements in an expanded manner.
  • Destructuring Object: Used to extract specific properties from an object and assign them to variables.

It should be noted that:

    The spread operator can only be used for iterable objects (arrays, objects, strings).
  • For arrays, the spread operator expands elements into independent items, while for objects, it expands properties and values.
  • The spread operator is useful in shallow copying, which means that it only copies the first-level properties of an object and does not copy nested properties.

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