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】
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