Countdown var to loop and display array_问答_开发者

开发者 https://www.devze.com 2023-03-06 14:47 出处：网络

I\'m very new to javascript and I\'m trying to do something I thought would be very basic. I\'ve created a countdown timer and used \"i\" as my variable to hold a number from 0-5. And I have an array

相关专题：javascript

I'm very new to javascript and I'm trying to do something I thought would be very basic.

I've created a countdown timer and used "i" as my variable to hold a number from 0-5. And I have an array of "d" from d[0] to d[5] containing strings.

I'm trying to make the timer countdown pass the "i" value into an innerHTML method array value so I want it to display d[5]... d[4]...开发者_高级运维d[3]... etc.

What am I doing wrong!? Please Help!

<html><head><script language="javascript" type="text/javascript">

var d=new Array():
    d[1]="One";
    d[2]="Two";
    d[3]="Three";
    d[4]="Four";
    d[5]="Five";

    var i=5;

    var i=setInterval("timer()",2000); //1000 will  run it every 1 second

    function timer() {
        i--;
        if (i <= 0)

 clearInterval(countD);
 return;
      }
 }

 document.getElementById(timer).innerHTML = d[i];

 </script>

 </head>
 <body>

 <h1>
 <p id="timer"></p>
 </h1>

 </body>
 </html>

Also, document.getElementById(timer).innerHTML = d[i];

should be document.getElementById("timer").innerHTML = d[i];

id names need to have quotes around them because they are not names of variables. The variable 'timer' is undefined.

Also, you are missing a curly brace on the line if (i <= 0). I am assuming that you meant to exit the function if this if statement is true.

Also, you have a colon instead of a semicolon on the line var d=new Array():

Also, you can't have a paragraph tag inside of an h1

Also, you should encapsulate all of this javascript into a function called something like init. I believe that the javascript code in the head runs before the html is loaded. The javascript can't therefore find the

tag. Then, use <body onload="init()"> as your body tag.

EDIT: As the commenters have stated, you are using the variable i for multiple unrelated things.

I'm sorry to say but your code is quite a mess; here's one way to get your code to work, along with a working example:

<html>
<head>
 <script language="javascript" type="text/javascript">
    var d=new Array();
    d[0]="One";
    d[1]="Two";
    d[2]="Three";
    d[3]="Four";
    d[4]="Five";

    var i=4;

    var myTimer =setInterval(timer,2000); //1000 will  run it every 1 second

    function timer() {
        document.getElementById("timer").innerHTML = d[i];
        i--;
        if (i < 0){
            clearInterval(myTimer);
        }
    }
 </script>
 </head>
 <body>
    <h1>
        <p id="timer"></p>
    </h1>
 </body>
 </html>

The problems with your JavaScript

You've got two declarations for i, one after the other - one is set to 5 and the other to the setInterval timer
What is countD in clearInterval(countD);?
document.getElementById(timer).innerHTML = d[i]; is attempting to use the function timer as the argument to getElementById. It should be in quotes: document.getElementById("timer").innerHTML = d[i];
- It is also being invoked only once since it's not inside the function that is being called by the timer.
var d=new Array(): should be terminated by a ;(semi-colon) and not a : (colon)
You have unmatched braces - your if statement doesn't have an opening brace ({) but it does have a closing one.
Note that while setInterval("timer()", 1000) is valid JavaScript, it depends on eval which should be avoided if possible. The alternate, preferred way to use this is setInterval(timer, 1000) i.e. passing the function and not a string.