JavaScript: String Methods for Regex
Regex is used for matching text patterns.
There are 2 ways to use regex in JavaScript:
- String's regex methods.
- Regex object's methods. 〔➤see JavaScript: RegExp Object〕
String Methods for Regex
| syntax | description |
|---|---|
s.replace(find_str,replace_str) | Returns a new string. The first occurrence of find_str in string s is replaced by string replace_str. (no regex) If no match, the original string is returned. 〔➤see JavaScript: String.prototoype.replace〕 |
s.replace(regex_obj,replace_str_or_func) | Return a new string. The replace_str_or_func can be a string or function.
If string, {$1, $2, …} refers to captured group. If function, it'll receive args: {matched substring, capture group 1, capture group 2, …}. If no match, the original string is returned.
ES5 §15#sec-15.5.4.11
〔➤see JavaScript: String.prototoype.replace〕
|
| syntax | description |
|---|---|
s.search(/…/) or s.search("…") | Return the index of first char of matched string. If no match, returns -1. If the argument is a string, it is converted to a regex object. ES5 §15#sec-15.5.4.12
〔➤see JavaScript: String.prototoype.search〕 |
| syntax | description |
|---|---|
s.match(/…/) or s.match("…") | Return a array of captured patterns. Index 0 is the whole matched string, index 1 is first captured pattern, …. Or, return null if no match. If the argument is a string, it is converted to a regex object. ES5 §15#sec-15.5.4.10
〔➤see JavaScript: String.prototoype.match〕 |
s.match(/…/g) | Return a array of all occurrences of matched string (note the g flag for global), or null if no match.
〔➤see JavaScript: String.prototoype.match〕 |
The syntax for regex is /pattern/flags (using slash as delimiter, not quotation symbol). It is a literal expression for regex object.
If a string "pattern" is given as argument:
- the “replace” method will treat it as literal string and do literal find/replace
- “search” and “match” methods will just automatically convert it into a regex object.