基于 window.innerWidth 设置中间弹窗

Question

I want to create a pop-up and I want to get it always positioned at the middle, no matter what the browser or screen-size be.

So for that, I am using window.innerWidth, but I don't know why this code isn't working.

function show_update_profile()
   {
       document.getElementById('black_fade').style.display='block';
       alert(window.innerWidth);
       document.getElementById('div_register').style.display='block';
       document.getElementById.('div_register').style.left= ((window.innerWidth)-500)/20;
       alert(window.innerWidth);
   }

The line document.getElementById.('div_register').style.left= ((window.innerWidth)-500)/20; is having the problem.

Answer 1

window.innerWidth is not cross browser compatible so it will not work with every browser, so you need a function like this

function getBrowserInnerSize(w)
{
    var x,y;
    if (!w){
        w = window;
    }

    if (w.innerHeight){ 
        // FireFox
        x = w.innerWidth;
        y = w.innerHeight;
    } else if (w.document.documentElement && w.document.documentElement.clientHeight) {
        // IE Strict mode
        x = w.document.documentElement.clientWidth;
        y = w.document.documentElement.clientHeight;
    } else if (w.document.body) {
        // IE Normal mode
        x = w.document.body.clientWidth;
        y = w.document.body.clientHeight;
    }

    return {"x":x,"y":y};
}