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How to use from function

不言Original: 2019-02-21 17:36:574908browse

The array.from() function is a built-in function in How to use from function that creates a new array instance from the given array. For strings, each alphabet of the string is converted to an element of the new array instance; for integer values, the new array instance takes an element of the given array. Let's look at the specific usage of from().

from() has two syntaxes

Syntax 1:

Array.from(A)

A can be an array for conversion to an array or a string, where each letter of the string is converted to an element of a new array instance.

Syntax 2:

Array.from（mapFn，thisArg）

mapFn (optional): Map function, used to call each element of the array.

thisArg (optional): Use this value when executing mapFn.

Let’s look at specific examples

Here we output creates a new array with the same content as the input in the case of integers but in the case of strings , each alphabet of the string is converted to an element of a new array instance.

The code is as follows

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title></title>
</head>
<body>
<script> 
console.log(Array.from("php中文网")); 
console.log(Array.from([10, 20, 30])); 
</script> 
</body>
</html>

The execution effect is as follows

How to use from function

Finally we need to pay attention to Is:

If we pass a complex number as a parameter, an error is returned because only arrays and strings can be taken as parameters.

Whenever we need to perform any operation on the elements of the array, we can use the Array.from() method in javaScript to achieve it.

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