Only execute a function if body class exists

Question

I have a body class like this:

<body class="horizontal">

I try to target with the following code:

'use strict';

// Horizontal scrolling
// http://www.dte.web.id/2013/02/event-mouse-wheel.html
(function() {
if(document.body.className === 'horizontal') {
  alert('It exists');

  function scrollHorizontally(e) {
    e = window.event || e;
    var delta = Math.max(-1, Math.min(1, (e.wheelDelta || -e.detail)));
    // Scroll to the left or right in `document.documentElement` and `document.body`
    document.documentElement.scrollLeft -= (delta * 75); // Multiplied by 75
    document.body.scrollLeft -= (delta * 75); // Multiplied by 75
    e.preventDefault();
  }
  if (window.addEventListener) {
    window.addEventListener('mousewheel', scrollHorizontally, false); // IE9, Chrome, Safari, Opera
    window.addEventListener('DOMMouseScroll', scrollHorizontally, false); // Firefox
  } else {
    window.attachEvent('onmousewheel', scrollHorizontally); // IE 6/7/8
  }
};
})();

But this is just not working. The alert not popping up. I would like to prefer a pure javascript solution, to not include Jquery because of this.

EDIT: I uncommented the horizontal scroller function, then it's working. So the script is causing the issue.

The entire script is called at the bottom of the body.

Is this JavaScript code before or inside of the `` tag? You'll need to show a complete web page with HTML and ` — apsillers, Feb 17 '16 at 19:15
[How to use the console](https://developer.chrome.com/devtools/docs/console) — adeneo, Feb 17 '16 at 19:17
your code is working check this >> https://jsfiddle.net/vp6htpf8/ as others said you have to put { — Vivek Solanki, Feb 17 '16 at 19:18
You would be better off using `document.body.classList.contains('horizontal')`. — , Feb 17 '16 at 19:18
@VivekSolanki Yes, with the “load type” set to “onload”, it obviously works. — Sebastian Simon, Feb 17 '16 at 19:18
The `scrollHorizontally` function is irrelevant if you want the alert to popup. Check your console for errors because there's something else going on if it isn't failing when you include that script. — Mike Cluck, Feb 17 '16 at 19:20
No it's not, because I uncommented it than the script is executing the alert, but if `scrollHorizontally` present, then even `alert` not executing. — Lanti, Feb 17 '16 at 19:21
duplicate of [Uncaught SyntaxError: In strict mode code, functions can only be declared at top level or immediately within another function](http://stackoverflow.com/questions/24573061/uncaught-syntaxerror-in-strict-mode-code-functions-can-only-be-declared-at-top) — apsillers, Feb 17 '16 at 19:38

score 0 · Accepted Answer · answered Feb 17 '16 at 19:24

0

just remove "'use strict';" and it will work see this

answered Feb 17 '16 at 19:24

Vivek Solanki

452
1
7
10

It works! Thank You! Can you give me an explanation why causing this? – Lanti Feb 17 '16 at 19:25
No, with use strict it only runs if I uncommenting `scrollHorizontally` (which why I got lots of downvoting, because the "smart ones" thought presenting in the code that part was irrelevant to the question). I use Firefox latest. https://jsfiddle.net/vp6htpf8/3/ – Lanti Feb 17 '16 at 19:28
@apsillers Firefox 44.0.2 x64 Running this there's NO ANY ALERT, just only if I uncommenting the `scrollHorizontally`: https://jsfiddle.net/vp6htpf8/2/ – Lanti Feb 17 '16 at 19:31
@apsillers yeah same for me , browser is causing the problem – Vivek Solanki Feb 17 '16 at 19:31
Than I officialy want rehabilitation with upvotes. :D – Lanti Feb 17 '16 at 19:32
3

@Lanti You've already been told to look in the browser's error console (press ctrl-shift-K). The error message would have told you immediately what the problem is ("in strict mode code, functions may be declared only at top level or immediately within another function"). – JJJ Feb 17 '16 at 19:34
I checked in Chrome finally, it works and there's no console errors. Firefox giving the console error that you described. – Lanti Feb 17 '16 at 19:36

Only execute a function if body class exists

1 Answers1