setInterval Method in Javascript

The setInterval() method evaluates a function or an expression repeatedly for the specified number of milliseconds and it returns an interval reference.

Syntax:

variable = setInterval(expression, milliseconds)

or

variable = setInterval(function, milliseconds)

variable holds the interval reference returned by seInterval method.

Example:
Below example display the current time information using setInterval method call the date object.

<html>
<head>
<title> setInterval Method Example </title>
<script language="javascript">
  function startSetInt()
  {
    ref=setInterval("init()",100);
  } 
 
  function init()
  {
    dt = new Date();
    document.getElementById("lbl").innerText = "Timer : " + dt;
    document.getElementById("btnStart").disabled = true;
    document.getElementById("btnStop").disabled  = false;
  }
 
  function stopSetInt()
  {
    clearInterval(ref)
    document.getElementById("lbl").innerText = "Timer : ";
    document.getElementById("btnStart").disabled = false;
    document.getElementById("btnStop").disabled = true;
  }
</script>
</head>
 
<body onload="startSetInt()">
<label id="lbl" name="lbl"></label>
</br>
</br>
 
<input type="button" id="btnStart" value="Start" onclick="startSetInt()" />
<input type="button" id="btnStop" value="Stop" onclick="stopSetInt()" />
 
</body>
</html>

Demo : Click here