Using Google Chrome, if you console.log an object, it lets you inspect the element in the console. For example:
var a = { "foo" : "bar", "whiz" : "bang" };
console.log(a);
This prints out Object which can be inspected by clicking on arrows next to it. If however I try to log an HTMLElement:
var b = goog.dom.query('html')[0];
console.log(b);
This prints out <html></html> which can not be inspected by clicking on arrows next to it. If I want to see the JavaScript object (with its methods and fields) instead of just the DOM of the element, how would I do that?
Use console.dir:
var element = document.documentElement; // or any other element
console.log(element); // logs the expandable <html>…</html>
console.dir(element); // logs the element’s properties and values
If you’re inside the console already, you could simply type dir instead of console.dir:
dir(element); // logs the element’s properties and values
To simply list the different property names (without the values), you could use Object.keys:
Object.keys(element); // logs the element’s property names
Even though there’s no public console.keys() method, if you’re inside the console already, you could just enter:
keys(element); // logs the element’s property names
This won’t work outside the console window, though.
来源：https://stackoverflow.com/questions/9633835/how-can-i-log-an-html-element-as-a-javascript-object