Check if the browser supports document.querySelect

问题:

Now although most modern browser support document.querySelectorAll(), you may run into problems with older versions of Internet Explorer. The obvious way of checking if the browser supports a function would be:

if(document.querySelectorAll){
    //some random code
}

But from what I understand some browsers like (IE8) don't support certain properties, like 'body *'. Is there a better way to check if document.querySelectorAll('body *') will actually work?

回答1:

document.querySelectorAll will thrown on any unsupported selector so you can simply use a try-catch block.

回答2:

test Browser support or not , without try-catch

function supportsQuerySelectors() {
  return (document['querySelector']&&document['querySelectorAll'])!=null;
}

or

function supportsQuerySelectors2(){
  return typeof(document['querySelector'])=='function'&&typeof(document['querySelectorAll'])=='function';
}

thanx : http://htmlgoodies.com/beyond/javascript/using-javascripts-css3-selectors.html

回答3:

Use typeof to check it:

 if(typeof(document.querySelectorAll) != 'undefined'){
      //some random code
 }