Summary of the JavaScript Length attribute, javascriptlength

Summary of the JavaScript Length attribute, javascriptlength

For a summary of the javascript length attribute, see the following details.

1. length in StringObject

The length attribute returns the number of characters in a string.

For example:

// Normal string var str = "abcdef"; console. log (str. length); // 6 // Array var str1 = new Array (1, 2, 3, 4); console. log (str1.length); // 4 // array and string var str2 = str1 + str; // "abcdef1, 2,3, 4" console. log (str2.length); // 13 // object and object var obj ={}; console. log (obj. length); // undefinedvar obj + = obj; // "[object Object] [object Object]" console. log (obj. length); // 30

Ii. length in Function

Length can return the number of function parameters.

Var a = function (a, B, c, d) {}; console. log (. length); // 4var B = RegExp; console. log (B. length); // The new RegExp (pattern, attributes) constructor has two parameters, so length is 2

※The length attribute of the arguments instance is the actual number of parameters that the caller passes to the function.

var a = function(){  console.log(arguments.length); };a(1,2,3); // 3a(); // 0

Note: As we all know, there is no method overload in javascript, and the arguments instance can help us simulate method overloading.

The following example shows the javascript length attribute.

Definition and usage

The length attribute returns the number of characters in a string.

Syntax

StringObject. length

Instance

In this example, we will show how to use the length attribute to return the characters in the string:

<script type="text/javascript">var txt="Hello World!"document.write(txt.length)</script>

Output:

12

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