variable scope issue with javascript

Question

In my application, originally those codes works:

var htm = "<div> My content </div>";   
$("#divprint").html(htm);
window.setTimeout('window.print()', 4000);

however, when I try to wrap it within an if statement, it won't print:

var canprint= $.cookie("actionprint");  
alert("I am outside " + canprint);
if(canprint == null){
    alert("I am inside");
    var htm = "<div> My content </div>";
    window.setTimeout('window.print()', 4000);
}

when I run this codes, I only got first alert: "I am outside null"

As javascript's scope is function level, I am wondering, why that if failed?

I don't see any function definition in your code. Btw, `console.log(typeof canprint, canprint);` — zerkms, Jan 23 '14 at 04:29
did you forget a double quotation mark on the declaration of variable htm? — gigadot, Jan 23 '14 at 04:31
`$.cookie()` for the props that don't exist returns `undefined`. — Ram, Jan 23 '14 at 04:32
That's not the reason. `null == undefined` is true, so it should go into the `if`. — Barmar, Jan 23 '14 at 04:37
Hi BlackSheep, I've tried canprint ==undefined, doesn't work.... — JavaScripter, Jan 23 '14 at 05:04

score 1 · Answer 1 · answered Jan 23 '14 at 04:46

1

Can you try the if statement like,

if (!canprint)

answered Jan 23 '14 at 04:46

vasudevanp

215
3
8

JavaScripter · Accepted Answer · 2014-01-23T05:34:14.780

1

OK. As weird it is:

Firstly, I tried to print out:

  console.log(typeof canprint, canprint);

amazingly, result is:

string null

so, I changed to if condition to:

if(canprint == "null")

then it can goes inside that if.

Though this is working, does anyone who can explain what has happened? This is really out of my expedition.

edited Jan 23 '14 at 05:34

answered Jan 23 '14 at 05:24

JavaScripter

4,282
9
37
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score 0 · Answer 3 · edited May 23 '17 at 12:23

0

Remove the quote and parenthesis from setTimeout function

window.setTimeout(window.print, 4000);

And use something like this: jQuery check if Cookie exists, if not create it

var CookieSet = $.cookie('cookietitle', 'yourvalue');

     if (CookieSet == null) {
          // Do Nothing
     }
     if (jQuery.cookie('cookietitle')) {
          // Reactions
     }

edited May 23 '17 at 12:23

Community

1
1

answered Jan 23 '14 at 04:31

Bhojendra Rauniyar

83,432
35
168
231

Although this is a reasonable suggestion, it isn't necessary; the original call will also work. It doesn't answer the question. – Barmar Jan 23 '14 at 04:35
This doesn't seem right. It sets the cookie before checking if it's already set. – Barmar Jan 23 '14 at 04:40

variable scope issue with javascript

3 Answers3