JavaScript String

String object is used to process existing character blocks.

JavaScript String

A string is used to store a sequence of characters like "John Doe".

A string can use single quotes or double quotes :

Instance

var carname="Volvo XC60";
var carname='Volvo XC60';

You can access any character in the string using position (index):

Example

var character= carname[7];

The index of the string starts from zero, so the first character of the string is [0], the second character is [1], and so on.

You can use quotation marks in strings, as shown below:

Example

var answer="It's alright";
var answer="He is called 'Johnny'";
var answer='He is called "Johnny"';

Or you can use escape characters in the string using quotes:

Instance

<!DOCTYPE html>
<html>
<head> 
<meta charset="utf-8"> 
<title>php中文网(php.cn)</title> 
</head>
<body>

<script>
var carname1="Volvo XC60";
var carname2='Volvo XC60';
var answer1="It's alright";
var answer2="He is called 'Johnny'";
var answer3='He is called "Johnny"';
document.write(carname1 + "<br>")
document.write(carname2 + "<br>")
document.write(answer1 + "<br>")
document.write(answer2 + "<br>")
document.write(answer3 + "<br>")
</script>

</body>
</html>

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String

String uses the length attribute length to calculate the length of the string:

Example

<!DOCTYPE html>
<html>
<head> 
<meta charset="utf-8"> 
<title>php中文网(php.cn)</title> 
</head>
<body>

<script>
var txt = "Hello World!";
document.write("<p>" + txt.length + "</p>");
var txt="ABCDEFGHIJKLMNOPQRSTUVWXYZ";
document.write("<p>" + txt.length + "</p>");
</script>

</body>
</html>

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Find the string in the string

Strings use indexOf() to locate the first occurrence of a specified character in the string:

Example

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>php中文网(php.cn)</title>
</head>
<body>

<p id="p1">Click the button to locate where "locate" first occurs.</p>
<p id="p2">0</p>
<button onclick="myFunction()">点我</button>
<script>
function myFunction(){
	var str=document.getElementById("p1").innerHTML;
	var n=str.indexOf("locate");
	document.getElementById("p2").innerHTML=n+1;
}
</script>

</body>
</html>

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If the corresponding character function is not found, the function returns -1

lastIndexOf() method in the string Find the occurrence of the string starting from the end.

Content matching

match()The function is used to find a specific character in a string, and if found, returns the character.

Instance

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>php中文网(php.cn)</title>
</head>
<body>

<script>
var str="Hello world!";
document.write(str.match("world") + "<br>");
document.write(str.match("World") + "<br>");
document.write(str.match("world!"));
</script>

</body>
</html>

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Replace content

replace() method replaces some characters with other characters in a string.

Instance

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>php中文网(php.cn)</title>
</head>
<body>

<p>替换 "Microsoft" 为 "php.cn" :</p>
<button onclick="myFunction()">点我</button>
<p id="demo">请访问 Microsoft!</p>
<script>
function myFunction() {
    var str = document.getElementById("demo").innerHTML; 
    var txt = str.replace("Microsoft","php.cn");
    document.getElementById("demo").innerHTML = txt;
}
</script>

</body>
</html>

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String case conversion

String case conversion uses the functiontoUpperCase() / toLowerCase():

Instance

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>php中文网(php.cn)</title>
</head>
<body>

<script>
var txt="Hello World!";
document.write("<p>" + txt.toUpperCase() + "</p>");
document.write("<p>" + txt.toLowerCase() + "</p>");
document.write("<p>" + txt + "</p>");
</script>
<p>该方法返回一个新的字符串，源字符串没有被改变。</p>

</body>
</html>

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Convert string to array

Use strong>split() function to convert string to array:

Example

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>php中文网(php.cn)</title>
</head>
<body>

<p id="demo">单击按钮显示数组。</p>
<button onclick="myFunction()">点我</button>
<script>
function myFunction(){
	var str="a,b,c,d,e,f";
	var n=str.split(",");
	document.getElementById("demo").innerHTML=n[0];
}
</script>

</body>
</html>

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Special characters

You can use the backslash (\) to insert special characters in Javascript Symbols, such as apostrophes, quotation marks and other special symbols.

View the following JavaScript code:

var txt="We are the so-called "Vikings" from the north.";
document.write(txt);

In JavaScript, strings start and stop using single or double quotes. This means that the above string will be cut into: We are the so-called

To solve the above problem, you can use backslashes to escape the quotes:

var txt ="We are the so-called \"Vikings\" from the north.";
document.write(txt);

JavaScript will output the correct text string: We are the so-called "Vikings" from the north.

The following table lists other special characters. You can use backslashes to escape special characters:

##\\ Slant bar\nLine break\rEnter\ttab\ bSpace##\f

Code	Output
\'	Single quotes
\"	Double Quotation marks





Page feed

characters String properties and methods

Properties:

##fromCharCode()
indexOf()
lastIndexOf()
match()
replace()
##search()
slice()
split()
substr()
substring()
##toLowerCase()
toUpperCase()
valueOf()

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