Properties and methods of String object in JavaScript

Properties and methods of String object

## length: Get the string length. For example: var len = strObj.length
toLowerCase(): Convert the letters in the string to all lowercase. For example: strObj.toLowerCase()
toUpperCase(): Convert the letters in the string to all uppercase. Such as: strObj.toUpperCase()

<!DOCTYPE HTML>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
        <title>php.cn</title>
        <script>
           var str="ASDfgh";
           document.write(str.length+"<br/>");
           document.write(str.toLowerCase()+"<br/>");
           document.write(str.toUpperCase()+"<br/>");
        </script>
    </head>
    <body>
    </body>
</html>

##charAt(index)

<!DOCTYPE HTML>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
        <title>php.cn</title>
        <script>
           var str="Hello JavaScript";
            for(var i=0;i<str.length;i++){
                document.write(str.charAt(i)+"<br/>");
            }
        </script>
    </head>
    <body>
    </body>
</html>

##indexOf()

Function: Return the index value of a substring in the original string (the search order is from left to right). If not found, -1 is returned.

Syntax: strObj.indexOf(substr)
Parameters: substr represents a substring to be found.

<!DOCTYPE HTML>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
        <title>php.cn</title>
        <script>
           var str="Hello JavaScript";
           document.write(str.indexOf("J")+"<br/>");   
           document.write(str.indexOf("S")+"<br/>");   
           document.write(str.indexOf("s")+"<br/>");   
        </script>
    </head>
    <body>
    </body>
</html>

lastIndexOf()

Function : In the original string, search for a certain substring from right to left. If not found, -1 is returned.

Syntax: strObj.lastIndexOf(substr)
Parameters: substr represents the substring to be found.

<!DOCTYPE HTML>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
        <title>php.cn</title>
        <script>
           var str="Hello JavaScript";
           document.write(str.lastIndexOf("J")+"<br/>");   
           document.write(str.lastIndexOf("S")+"<br/>");   
           document.write(str.lastIndexOf("s")+"<br/>");   
        </script>
    </head>
    <body>
    </body>
</html>

##substr()

Function: In the original string, return a substring.

Syntax: strObj.substr(startIndex [ , length])
Description: Return length characters starting from the subscript startIndex.
Parameters:

length is optional, how many characters are returned. If omitted, always returns to the end.

<!DOCTYPE HTML>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
        <title>php.cn</title>
        <script>
           var str="Hello JavaScript";
           document.write(str.substr(6)+"<br/>");
           document.write(str.substr(6,4)+"<br/>");               
        </script>
    </head>
    <body>
    </body>
</html>

##substring()

Function: In the original string, return a substring.

Syntax: strObj.substring(startIndex [, endIndex])
Description: Returns the starting index value from startIndex to the end index value of endIndex all characters between.
parameter:

startIndex: represents the start index value.
endIndex: optional, representing the end index value. If omitted, all characters up to the end are generally returned.

Note: If the second parameter is omitted, the results of substr() and substring() are the same.

Note: The characters returned by substring() include the characters at startIndex and do not include the characters at endIndex.

<!DOCTYPE HTML>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
        <title>php.cn</title>
        <script>
           var str="Hello JavaScript";
           document.write(str.substring(6)+"<br/>");
           document.write(str.substring(6,10)+"<br/>");               
        </script>
    </head>
    <body>
    </body>
</html>

split(): Convert a string into an array

Function: Cut a string into several segments. Returns an array.
Syntax: strObj.split (split number)
Parameters: The parameter is a string of split numbers. Cut the string into segments using the specified split number.

Use a space as the dividing number to divide the string Hello JavaScript
into an array Hello, JavaScript

<!DOCTYPE HTML>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
        <title>php.cn</title>
        <script>
           var str="Hello JavaScript";
           document.write(str.split(" "))           
        </script>
    </head>
    <body>
    </body>
</html>

Continuing Learning

new file

<!DOCTYPE HTML> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <title>php.cn</title> <script> var str="ASDfgh"; document.write(str.length+"<br/>"); document.write(str.toLowerCase()+"<br/>"); document.write(str.toUpperCase()+"<br/>"); </script> </head> <body> </body> </html>

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Properties and methods of String object in JavaScript

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