What do three dots mean in vue

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.

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>

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>

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>

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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