Analysis of how to reverse numbers through javascript-JS Tutorial-php.cn

Analysis of how to reverse numbers through javascript

藏色散人

Release： 2021-08-10 11:26:04

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"Reverse numbers" means outputting numbers in reverse order. For example, a number 12345, after reversal, is 54321; then in "Quickly reverse and output a positive integer through a PHP program" we explain how Reverse a number through PHP. Friends who are interested can learn about it~

The focus of this article is to explain how to reverse a number through javascript.

Without further ado, I will go directly to the code:

javascript to reverse the numbers:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title></title>
</head>
<body>
<script>
    function reverse_a_number(n)
    {
        n = n + "";
        return n.split("").reverse().join("");
    }
    console.log(reverse_a_number(32243));

</script>
</body>
</html>

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Then open the console to view the reversal result ：

Analysis of how to reverse numbers through javascript

In the above code, I gave an example number "32243", which is obviously reversed to "34223".

In the js code in the above example, you need to master 3 methods:

1.split() method: used to split a string into a string array, its syntax is " stringObject.split(separator,howmany)”;

parameters respectively represent:

separator，字符串或正则表达式，从该参数指定的地方分割 stringObject。
howmany，该参数可指定返回的数组的最大长度。如果设置了该参数，返回的子串不会多于这个参数指定的数组。如果没有设置该参数，整个字符串都会被分割，不考虑它的长度。

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→Note: If an empty string ("") is used as separator, then each character in stringObject will be separated. String.split() performs the opposite operation of Array.join .

2.reverse() method: used to reverse the order of elements in an array, its syntax is "arrayObject.reverse()";

→Note: This method will change the original array but not create a new array.

3.join() method: used to put all the elements in the array into a string. The elements are separated by the specified delimiter. The syntax is "arrayObject. join(separator)"; its parameter separator specifies the separator to be used; if this parameter is omitted, a comma is used as the separator.

Finally, I would like to recommend "JavaScript Basics Tutorial" ~ Welcome everyone to learn ~

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