String indexOf()

indexOf() searches a string and return the position. indexOf() returns -1 if the substring isn't found.

indexOf() method does the search at the beginning.

 
<!DOCTYPE html>
<html>
<head>
    <title>Example</title>
    <script type="text/javascript">
    
        var stringValue = "hello world"; 
        document.writeln(stringValue.indexOf("o")); //4 

       
    </script>
</head>
<body>
</body>
</html>

Click to view the demo

An optional second argument tells where to start with.

 
<!DOCTYPE html>
<html>
<head>
    <title>Example</title>
    <script type="text/javascript">
    
        var stringValue = "hello world"; 
        document.writeln(stringValue.indexOf("o", 6)); //7 

       
    </script>
</head>
<body>
</body>
</html>

Click to view the demo

 
<!DOCTYPE html>
<html>
<head>
    <title>Example</title>
    <script type="text/javascript">
    
        var stringValue = "Lorem ipsum dolor sit amet, consectetur adipisicing elit"; 
        var positions = new Array(); 
        var pos = stringValue.indexOf("e"); 
        
        while(pos > -1){ 
            positions.push(pos); 
            pos = stringValue.indexOf("o", pos + 1); 
        } 
        
        document.writeln(positions); //3,13,15,29
       
    </script>
</head>
<body>
</body>
</html>

Click to view the demo