admin管理员组

文章数量:1430493

I would like to give users the ability to increase/decrease the rendering size of the content inside of a web app.

The CTRL+ and CTRL- features (or CTRL1 through CTRL9) of Chrome & Firefox are handy - but is there a way from JavaScript to execute those features?

Clarification: I want the user to be able to achieve this via mouse-clicks, not keypresses, so something like this:

function resize_rendering() {
    // code that executes ctrl+ or crtl-
}

I would like to give users the ability to increase/decrease the rendering size of the content inside of a web app.

The CTRL+ and CTRL- features (or CTRL1 through CTRL9) of Chrome & Firefox are handy - but is there a way from JavaScript to execute those features?

Clarification: I want the user to be able to achieve this via mouse-clicks, not keypresses, so something like this:

function resize_rendering() {
    // code that executes ctrl+ or crtl-
}
  • javascript
  • firefox
  • google-chrome
Share Improve this question edited May 10, 2012 at 15:32 Xavier T. 42.4k10 gold badges75 silver badges99 bronze badges asked Jul 15, 2011 at 14:02 OneNerdOneNerd 6,55217 gold badges63 silver badges78 bronze badges 1
  • 1 I dont think you can mimic that feature of the browser since its a personal setting within the browser. The CTRL+/- actually zooms in on all parts even images. To do that with javascript you would have to increase the size of images and text on your site. What I've seen is people just increasing the font size, using Javascript.. but not the images. – Evan Larsen Commented Jul 15, 2011 at 14:06
Add a ment  | 

5 Answers 5

Reset to default 3

The browser zoom level is a user setting, which is there for accessiblity purposes; it's not intended for the site developer to ever know or care what the zoom level is, so I would expect that you'll have trouble doing exactly what you want. Certainly, it'll be hard to get it right in a way that works cross-browser.

The normal approach to this is to have a sizing gadget that changes the base font size.

If all the font sizes in your site are in em units, then you can change the sizes of all the text on the site with a single CSS change.

So you would have a set of buttons on the site which use Javascript to set the font-size of the <body> element to (for example) 12, 14, 16 or 18 pixels, depending on the element clicked.

There's a write-up of the technique here: http://labnol.blogspot./2006/12/allow-site-visitors-to-change-font.html

You are not allowed to by design. You can't change a user's browser setting via Javascript.

You can do other things, like modify all of the CSS on your page to scale everything down to simulate a CTRL-, but that's all.

In some browsers you can capture CTRL+/- before the browser does, allowing you to stop those events from occuring. But you cannot do the oppisite - you cannot cause those events to occur from your own script.

This library here by John Resig is a jQuery plugin that should do the job. There's some samples. Its quite easy to hookup binations of keys as well.

You could intercept the keystroke in a general key event handler (such as on the window object), check to see if it's the one you're looking for, and if so, call stopPropagation() on the event parameter (and return false) to prevent the browser from then handling it on its own.

You'd then have to perform the sizing operation yourself, such as by modifying a stylesheet using JavaScript.

window.addEventListener( 'keydown', function( e ) {
    if ( /* check e.keyCode etc. */ ) {
        // modify global style to increase/decrease font size
        e.stopPropagation();
        return false;
    } );

Look towards CSS property "zoom"

/* ctrl++ */
body {
   zoom: 1.1;
}

For JS, it's like:

function resize_rendering(zoom) {
   let currentZoom = parseFloat(document.body.style.zoom) || 1
   document.body.style.zoom = currentZoom * zoom
}

resize_rendering(1.1) // ctrl++
resize_rendering(0.9) // ctrl+-

本文标签： Use Javascript to CTRL and CTRL in Firefox amp ChromeStack Overflow

版权声明：本文标题：Use Javascript to CTRL+ and CTRL- in Firefox &amp; Chrome - Stack Overflow 内容由网友自发贡献，该文观点仅代表作者本人， 转载请联系作者并注明出处：http://www.betaflare.com/web/1745531731a2662092.html， 本站仅提供信息存储空间服务，不拥有所有权，不承担相关法律责任。如发现本站有涉嫌抄袭侵权/违法违规的内容，一经查实，本站将立刻删除。