javascript - this.getAttribute is not a function -

javascript - this.getAttribute is not a function -

i new javascript. want write javascript code when click button, alert window pops , writes data-message attribute. here code:

<button type="button" data-message="a1" onclick="pop()">click</button> <script> function pop() { alert(this.getattribute("data-message")); } </script>

but error

typeerror: this.getattribute not function alert(this.getattribute("data-message"));

i have 2 questions:

what wrong?

how can debug this? how can find out this refers to? using firebug.

thanks lot.

you need send this on button like

<button type="button" data-message="a1" onclick="pop(this)">click</button>

and js, capture calling it.

function pop(e) { alert(e.getattribute("data-message")); }

working demo

javascript