How can I execute a function on pressing the enter key in an <input> field?

I have an input and I'd simply like to add an event listener for it to activate a function when I press enter, when the input is focused. How do I do this with pure JS?

Right now I have:

HTML:

Enter your wage:<input type="text" id="wage" value ="" size=20>
<button id="sub">Submit</button>

JavaScript:

var wage = document.getElementById("wage");
wage.addEventListener("change", validate);

var btn = document.getElementById("sub");
btn.addEventListener("click", validate);

So basically the function validate() activates when I click OR change the text, but I want to call it by pressing enter.

Solution 1:

You can use this:

var wage = document.getElementById("wage");
wage.addEventListener("keydown", function (e) {
    if (e.code === "Enter") {  //checks whether the pressed key is "Enter"
        validate(e);
    }
});

function validate(e) {
    var text = e.target.value;
    //validation of the input...
}

Live demo here

Solution 2:

var elem = document.getElementById("wage");
elem.onkeyup = function(e){
    if(e.keyCode == 13){
       validate();
    }
}

Working Example http://jsfiddle.net/aMgLK/