On the _javascript technique of replace () method in JavaScript

Source: Internet
Author: User

Definitions and usage
The replace () method replaces some characters in a string with some other characters, or replaces a substring that matches a regular expression.
stringobject.replace (regexp/substr,replacement)

return value
A new string that is replaced with replacement for the first match of RegExp or after all matches have been made.
The replace () method of the string Stringobject performs a find-and-replace operation. It will look for substrings in the stringobject that match the regexp, and then replace them with replacement. If RegExp has global flag G, then the Replace () method replaces all matching substrings. Otherwise, it replaces only the first matching substring.

Replacement can be either a string or 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 string that is matched from the pattern will be used for substitution.

Note: ECMAScript v3 stipulates that the parameter replacement of the replace () method can be a function rather than 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 argument 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.
Example 1
In this case, we'll use "w3school" to replace "Microsoft" in the string:

<script type= "Text/javascript" >

var str= "Visit microsoft!"
document.write (Str.replace (/microsoft/, "jb51")


Output: Visit jb51!
Example 2
In this case, we will perform a global substitution, which is replaced with "W3school" whenever "Microsoft" is found:

<script type= "Text/javascript" >

var str= "Welcome to microsoft! "
Str=str +" We are proud to announce this is Microsoft has "
Str=str +" one of the largest WEB developers sites in t He world. "

document.write (Str.replace (/microsoft/g, "jb51")


Welcome to jb51! We are proud to announce that JB1

has one of the largest WEB developers sites in the world.
Example 3
You can use the code provided in this example to ensure that matching string uppercase characters are correct:

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

Output: JavaScript Tutorial
Example 4
In this case, we'll convert "Doe, John," to "John Doe" in the form of:

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

Output: John Doe
Example 5
In this case, we'll replace all the curly quotes with straight quotes:

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

Output: ' A ', ' B '
Example 6
In this case, we will convert the first letter of all words in the string to uppercase:

Name = ' AAA bbb CCC ';
Uw=name.replace (/\b\w+\b/g, function (word) {return
 word.substring (0,1). toUpperCase () +word.substring (1);}

Output: Aaa Bbb Ccc

Through this simple study, we should probably know the JavaScript replace () method, combined with the example practice, I hope to help you learn.

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