An example without end index

JavaScript / HTML/ CSS Code

Output

<!DOCTYPE html>
<html>
<head>
<style>
.substrdiv {
  background: #D26900;
  height: auto;
  width:300px;
  border-radius: 15px;
  padding:20px;
  font-size:16px;
  color:#fff;  
}
#substring {
    background: #5AB65A;
}
.paracls {
    background: #5AB65A;
}
.btncls{
    background-color:#4F6677;
    border: #2e6da4;
  	font-family: Arial, Geneva, Arial, Helvetica,  sans-serif;
	font-size: 15px;
    color: #FFFFFF;
    letter-spacing: 1px;
    padding: 8px 12px;
    font-size: 14px;
    font-weight: normal;

    border-radius: 4px;
    line-height: 1.5;
    text-decoration:none;
} 
</style>
</head>

<body>
<div class="substrdiv">Main String: "The JavaScript substring tutorial!" 
<p class="paracls">var str_sub = source_string.substring(4);</p>
<p>After substring method: <span id="substring"></span></p>

</div>

<p><button class="btncls" onclick="getsubstring()">Execute substring method</button></p>
<script type="text/javascript">
function getsubstring(){
var source_string = ("The JavaScript substring tutorial!");
var str_sub = source_string.substring(4);

document.getElementById("substring").innerHTML = str_sub;
}
</script>
</body>
</html>

Main String: "The JavaScript substring tutorial!"

var str_sub = source_string.substring(4);

After substring method: