TriggerShortcut "STRG + Plus-button" with Javascript

Question

To improve the user-experience for older Users, who do not know all the functions and shortcuts of their browser, I would like to have a button which simply triggers Ctrl++ (plus-button) to zoom in and improve the readability.

Is this possible?
How?
Is there a solution for Mac-users who do have an other button for Strg?

Edit: Seems like I could use the zoom property in CSS3.

I just tried:

function mzi(){

var oldval = document.getElementById('zoom').style.zoom;
var newval = Number(oldval) + 0.1;

alert('old value is '+Number(oldval)+' and new value is '+newval+'.');
document.getElementById('zoom').style.zoom = Number(oldval) + 0.1;

};

And it almost does what I want.

The problem:

It sets the zoom to 0.1 and not to "oldval + 0.1".

So the problem seems to be somewhere around the variable "oldval".

Maybe I cant store the value correctly or I cant use it correctly?

The alert says old value is 0 and new value is 0.1

To our non-German-speaking friends: *Strg* means *Ctrl*. – Frédéric Hamidi Feb 18 '15 at 15:32 — Frédéric Hamidi, Feb 18 '15 at 15:32
Oh yea. I am sorry. ^^ I edited it. :) – Nils Feb 18 '15 at 15:33 — Nils, Feb 18 '15 at 15:33
--> i edited the question and added more information – Nils Feb 18 '15 at 16:56 — Nils, Feb 18 '15 at 16:56

score 0 · Answer 1 · answered Feb 18 '15 at 15:40

0

Hello you can do it like this :

document.addEventListener("keypress", zoom, false);

function zoom(e) {
    var keyId = e.keyCode || e.which;
    if (keyId == 17 && keyId == 107 ) {
        window.parent.document.body.style.zoom += 1.5;// choose the factor of zoom

    }

answered Feb 18 '15 at 15:40

AngularLover

364
1
12

I do not know if this does what I want. It seems like it zooms when i press + or -. thats not what i wanted. ;) id like to create a button. if u click that button it zooms in or oout. – Nils Feb 18 '15 at 16:44
--> i edited the question and added more information – Nils Feb 18 '15 at 16:53
no it triggers ig Control + "+" is pressed. – AngularLover Feb 18 '15 at 17:35

TriggerShortcut "STRG + Plus-button" with Javascript

1 Answers1