JavaScript Replace () method

Source: Internet
Author: User

Definition and Usage

The replace () method is used to replace other characters with some characters in a string, or to replace a substring that matches a regular expression.

Stringobject.replace (regexp/substr,replacement)
Parameters Description

Necessary. A RegExp object that specifies the substring or pattern to replace.

Note that if the value is a string, it is used as the direct volume text pattern to be retrieved, instead of being converted to the RegExp object first.

Replacement Necessary. A string value. A function that specifies replacement text or generates alternate text.
return value

A new string that is obtained after the first match or all matches of regexp have been replaced with replacement.


The replace () method of the string Stringobject performs a find-and-replace operation. It looks for substrings in Stringobject that match regexp, and then replaces them with replacement. If RegExp has global flag G, then the Replace () method replaces all matching substrings. Otherwise, it replaces only the first matched substring.

Replacement can be a string, or it can be a function. If it is a string, then each match is replaced by a string. However, the $ character in replacement has a specific meaning. As shown in the following table, it shows that the resulting string from a pattern match will be used for substitution.

character Replace text
$, $ 、...、 The text that matches the 1th to 99th sub-expression in RegExp.
$& A substring that matches the regexp.
$` The text that is located to the left of the matching substring.
$ The text on the right side of the matching substring.
$$ Direct volume symbol.

Note: ECMAScript v3 stipulates that the parameter replacement of the replace () method can be a function instead of a string. In this case, each match calls the function, and the string it returns is used as the replacement text. The first parameter of the function is a string that matches the pattern. The next parameter is a string that matches the subexpression in the pattern and can have 0 or more of these parameters. The next argument is an integer that declares where the match appears in the Stringobject. The last parameter is the stringobject itself.

ExampleExample 1

In this example, we will replace "Microsoft" in the string with "W3school":

<script type= "Text/javascript" >var str= "Visit microsoft!" document.write (str.replace (/microsoft/, "W3school"))</script>
Visit w3school!
Example 2

In this example, we will perform a global substitution, and whenever "Microsoft" is found, it is replaced with "W3school":

<script type= "Text/javascript" >var str= "Welcome to microsoft! "str=str +" We is proud to announce, Microsoft has "str=str +" one of the largest Web developers si TES in the world. " document.write (str.replace (/microsoft/g, "W3school"))</script>


Welcome to w3school! We is proud to announce this W3schoolhas one of the largest WEB developers sites in the world.
Example 3

You can use the code provided in this example to ensure that the matching string is correct for uppercase characters:

Text = "JavaScript Tutorial"; Text.replace (/javascript/i, "JavaScript");
Example 4

In this example, we will convert "Doe, John" to the form of "John Doe":

Name = "Doe, John"; Name.replace (/(\w+) \s*, \s* (\w+)/, "$ $");
Example 5

In this example, we'll replace all the curly quotes with straight quotes:

name = ' A ', "B" '; Name.replace (/"([^"]*) "/g," ' $ ' ");
Example 6

In this example, we will convert all of the words in the string to uppercase in the first letter:

Name = ' aaa bbb ' CCC '; UWfunction(word)  {return word.substring (0,1). toUpperCase () +word.substring (1);}  );
Replace () 1
How to replace characters in a string with replace ().
Replace () 2-Global Search
How to use replace () for global substitution.
Replace () 3-case insensitive search
How to use replace () to ensure that uppercase letters are correct.
Replace () 4
How to use replace () to convert the name format.
Replace () 5
How to use replace () to convert quotation marks.
Replace () 6
How to use replace () to convert the first letter of a word to uppercase.

JavaScript Replace () method

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