how to use javascript onkeyup for multiple ids at sametime

Question

I have 2 html textbox for users to enter numbers. To sum those numbers, I am passing the values to JavaScript variable and after addition displaying the result to html div section ```

``` javascript: ``` document.getElementById('left').onkeyup = function() { var a = parseFloat(this.value); } document.getElementById('right').onkeyup = function() { var b = a + parseFloat(this.value); document.getElementById("result").innerHTML = b || 0 ; } ``` But I have an issue with JavaScript. It not displaying the result. How to add both functions in same onkeyup function. FIDDLE SETUP

Accepted Answer

Try this:

```
window.onload = function(){

var left = document.getElementById('left');
    var right = document.getElementById('right');
    var result = document.getElementById("result");

left.onkeyup = calc;
    right.onkeyup = calc;

function calc() {
        var a = parseFloat(left.value) || 0;
        var b = parseFloat(right.value) || 0;
        result.innerHTML = a + b ;
    }

}
```

JSFiddle: http://fiddle.jshell.net/gYV8Z/3/

Update: To hide the result in case the sum equals zero , change the last line like this:

```
        result.innerHTML = ( a + b ) || "";
```

JSFiddle: http://fiddle.jshell.net/gYV8Z/4/

how to use javascript onkeyup for multiple ids at sametime

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