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Detailed explanation of the use of charCodeAt() method in JavaSacript_Basic knowledge

WBOY
WBOYOriginal
2016-05-16 15:56:161581browse

This method returns a number representing the Unicode value of the character at the given index.

Unicode code points range from 0 to 1114111. A direct match of the ASCII character encoding of the first 128 Unicode code points. charCodeAt() will always return a value less than 65,536.
Grammar

string.charCodeAt(index);

Here are the details of the parameters:

  • index: an integer between 0 and 1 that is less than the length of the string; defaults to 0 if not specified.

Return value:

Returns a number representing the Unicode value of the character at the given index. If the given index is not a length between 0 and 1, NaN is returned.
Example: 

<html>
<head>
<title>JavaScript String charCodeAt() Method</title>
</head>
<body>
<script type="text/javascript">
var str = new String( "This is string" );
document.write("str.charCodeAt(0) is:" + str.charCodeAt(0)); 
document.write("<br />str.charCodeAt(1) is:" + str.charCodeAt(1)); 
document.write("<br />str.charCodeAt(2) is:" + str.charCodeAt(2)); 
document.write("<br />str.charCodeAt(3) is:" + str.charCodeAt(3)); 
document.write("<br />str.charCodeAt(4) is:" + str.charCodeAt(4)); 
document.write("<br />str.charCodeAt(5) is:" + str.charCodeAt(5)); 
</script>
</body>
</html>

This will produce the following results: 

str.charCodeAt(0) is:84
str.charCodeAt(1) is:104
str.charCodeAt(2) is:105
str.charCodeAt(3) is:115
str.charCodeAt(4) is:32
str.charCodeAt(5) is:105

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