Delaying While Loop in JavaScript

Question

<html>
<body>
<a href="" id = "content2">Click Here</a>
<body>
</html>

I am using the following code to check the href attribute of the anchor tag and if it is blank I want to show alert for now. But when I write the code of javaScript in web browser console my complete system ends up unresponsive for quite some time. I might be doing something wrong. Can someone explain me what?

var a = document.getElementById("content2").getAttribute("href");

let i = 0;
while(a.trim().length < 1)
{
     task(i);
}

function task(i) { 
  setTimeout(function() { 
      alert(i); 
  }, 1000 * 10); 
}

Why is the idea behind tracking changes over a href?, using while is a no no because it blocks the code execution (is a sync function). — Sebastián Espinosa
– Sebastián Espinosa, Commented May 10, 2020 at 5:39

PotatoParser · Accepted Answer · 2020-05-10 05:39:04Z

1

Your timeout call seems to be within a while loop which gets called a ton of times. It should be

var a = document.getElementById("content2").getAttribute("href");

let i = 0;

if (a.trim().length < 1) {
  task(i);
}

function task(i) {
  setTimeout(function() {
    alert(i);
    if (a.trim().length < 1) {
      task(++i);
    }
  }, 1000 * 10);
}

<html>
<body>
<a href="" id = "content2">Click Here</a>
</body>
</html>

This runs your loop after each attempt where a.trim().length < 1

answered May 10, 2020 at 5:39

PotatoParser

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Comments

Hien Nguyen · Accepted Answer · 2020-05-10 05:33:39Z

0

You need change while loop to if condition, the while loop have never ended.

var a = document.getElementById("content2").getAttribute("href");

let i = 0;
if(a.trim().length < 1)
{
     task(i);
}

function task(i) { 
  setTimeout(function() { 
      alert(i); 
  }, 1000 * 10); 
}

<html>
<body>
<a href="" id = "content2">Click Here</a>
<body>
</html>

answered May 10, 2020 at 5:33

Hien Nguyen

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2 Comments

Ravinder Yadav Over a year ago

But replacing if in place of while will execute the code only once. I want to execute the code every second not just once

Hien Nguyen Over a year ago

but you need change condition of while loop? do you want to loop until what

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