Home >Web Front-end >Front-end Q&A >What are the ways to use regular expressions in javascript?
Regular methods in JavaScript: 1. exec(), used to retrieve matches of regular expressions in strings; 2. test(), used to detect whether a string matches a specified regular expression; 3. toString(); 4. replace(); 5. match(); 6. search().
The operating environment of this tutorial: windows7 system, javascript version 1.8.5, Dell G3 computer.
What is regular expression
Regular expression is an object that describes a character pattern.
Regular expressions are used to match string patterns and retrieve and replace them. They are a powerful tool for performing pattern matching on strings.
RegExp Object Method
| Method | Description |
|---|---|
| compile | is deprecated in version 1.5. Compile regular expressions. |
| exec | Retrieve the value specified in the string. Returns the found value and determines its position. |
| test | Retrieve the value specified in the string. Returns true or false. |
| toString | Returns the string of the regular expression. |
Methods of String objects that support regular expressions
| Methods | Description | FF | IE |
|---|---|---|---|
| search | Retrieve values that match a regular expression. | 1 | 4 |
| match | Find a match for one or more regular expressions. | 1 | 4 |
| replace | Replace the substring that matches the regular expression. | 1 | 4 |
| split | Split the string into a string array. | 1 | 4 |
JavaScript exec() method
exec() method Used to retrieve matches of a regular expression in a string.
If there is a matching value in the string, return the matching value, otherwise return null.
var str="Hello world!";
//查找"Hello"
var patt=/Hello/g;
var result=patt.exec(str);
document.write("返回值: " + result);
//查找 "php"
patt=/php/g;
result=patt.exec(str);
document.write("<br>返回值: " + result);
JavaScript test() method
The test() method is used to test whether a string matches a certain pattern.
Returns true if there is a matching value in the string, otherwise returns false.
var str="Hello world!";
//查找"Hello"
var patt=/Hello/g;
var result=patt.test(str);
document.write("返回值: " + result);
//查找 "php"
patt=/php/g;
result=patt.test(str);
document.write("<br>返回值: " + result);
JavaScript RegExp toString() method
toString() method returns the string value of a regular expression.
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
</head>
<body>
<p>点击按钮返回正则表达式的字符串值。</p>
<button onclick="myFunction()">点我</button>
<p id="demo"></p>
<script>
function myFunction() {
var patt = new RegExp("PHP中文网", "g");
var res = patt.toString();
document.getElementById("demo").innerHTML = res;
}
</script>
</body>
</html>JavaScript replace() method
replace() method is used to replace some characters with other characters in a string , or replace a substring that matches a regular expression.
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
</head>
<body>
<p>单击按钮将段落中的“blue”替换成“red”。</p>
<p id="demo">Mr Blue has a blue house and a blue car.</p>
<button onclick="myFunction()">点我</button>
<script>
function myFunction(){
var str=document.getElementById("demo").innerHTML;
var n=str.replace(/blue/gi,"red");
document.getElementById("demo").innerHTML=n;
}
</script>
</body>
</html>JavaScript match() method
The match() method retrieves a specified value within a string, or finds a or multiple regular expression matches.
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
</head>
<body>
<p id="demo">单击按钮显示matches</p>
<button onclick="myFunction()">点我</button>
<script>
function myFunction(){
var str="The rain in SPAIN stays mainly in the plain";
var n=str.match(/ain/g);
document.getElementById("demo").innerHTML=n;
}
</script>
</body>
</html>JavaScript search() method
The search() method is used to retrieve a specified substring in a string, or Retrieve substrings that match a regular expression.
If no matching substring is found, -1 is returned.
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
</head>
<body>
<p id="demo">单击显示查找的位置</p>
<button onclick="myFunction()">点我</button>
<script>
function myFunction(){
var str="Mr. Blue has a blue house"
var n=str.search("blue");
document.getElementById("demo").innerHTML=n;
}
</script>
</body>
</html>
【Related recommendations: javascript learning tutorial】
The above is the detailed content of What are the ways to use regular expressions in javascript?. For more information, please follow other related articles on the PHP Chinese website!