Js timer instance sharing, js timer instance

Js timer instance sharing, js timer instance

1. Set the timer

Syntax: setInterval (function, time)

Note:

Function writing cannot contain parentheses

SetInterval (fn, 1000) // correct setInterval (fn (), 1000) // Error

The minimum time is not less than 14 ms.

2. Clear the timer

Syntax: clearInterval (the name of the cleared timer)

3. instance Exploration

Js Section

window.onload = function() { var timer = null; var num = 0; var i = 0;  var arr=['red','#FF9D0C','#DBFF0D','#3BFF0D','#0DFFA2','#0DE8FF','#0D52FF','#210DFF','#930DFF','#FF0DB4'] var start = document.getElementById('start'); var stop = document.getElementById('stop'); var prizeDraw = document.getElementById('prizeDraw'); start.onclick = function() { clearInterval(timer); timer = setInterval(function(){   num = Math.floor(Math.random()*100+1);  prizeDraw.style.backgroundColor = arr[i];  i++;  if (i==9) {  i = 0;  };  prizeDraw.innerHTML = num; },100); } stop.onclick = function() { clearInterval(timer); }}

Css Section

#prizeDraw {  width: 100px;  height: 100px;  background: rgba(255,68,253,0.5);  font-size: 30px;  text-align: center;  line-height: 100px;  }

Html section

<Div id = "prizeDraw"> </div> <input type = "button" value = "start" id = "start"> <input type = "button" value =" pause "id =" stop ">

Code Analysis:

Note that you must clear the timer before running the timer. Otherwise, if you keep clicking run timer, the timer will run multiple times and the timer will not stop;

ClearInterval () values that can be cleared are null;

Store the content in the array.

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