获取窗口宽度javascript

Question

I am trying to measure the width of the current viewport to set variable thisWidth but getting 'undefined'

var thisWidth;
var browserWidth = $(window).width();

if(browserWidth > 590){
    var thisWidth= 180;
} else if(browserWidth > 350){
    var thisWidth= 150;
}

alert(thisWidth); // undefined??

Is there a better way to do this?

The reason I am doing it is to change a width variable(thisWidth) based on viewport width whether it be mobile or whatever.

UPDATE - SOLVED Problem was, it was measuring before it had finished loading! Therefore coming in below 350 where finished width was 360 - weird actually

Answer 1

执行“jQuery ready”中的代码：

$(function(){ // Your code here })

Answer 2

The var s are redundant since they make variables local to the function scope . They don't hurt, but make the code less clear.

I'm guessing you are missing a default value if browserWidth happens to be > 350

Answer 3

As others have pointed out, the extra var s are unnecessary and can be removed. If you look at the logic, there's one case where thisWidth can be undefined after the if. What happens if browserWidth is less than or equal to 350? Then neither of the assignments to thisWidth will run. Add a final else to fix it.

var thisWidth;
var browserWidth = $(window).width();

if(browserWidth > 590){
    thisWidth= 180;
} else if(browserWidth > 350){
    thisWidth= 150;
} else {
    thisWidth=42;
}

alert(thisWidth);