jquery: test whether input variable is dom element

Question

I would like to write a jquery function that accepts either a dom element or its id as input:

function myfunction(myinput){
 // pseudocode:
 // if (myinput is dom element){
 //   var myID = $(myinput).attr('id');
 // } else {
 //   var myID = myinput;
 // }

 // Do stuff with myID ...

}

Question: How can I tell whether myinput is a dom element???

This has already been asked: stackoverflow.com/questions/384286/… — Piksel8
– Piksel8, Commented Feb 17, 2011 at 20:37

Tom Tu · Accepted Answer · 2011-02-17 20:40:59Z

21

It's easier to do the check the other way around - check if it's a string if so use it to get an ID else treat it as a DOM node/element and handle it as if it was one.

function myfunction(myinput) {

    var myId;

    if (typeof myinput == 'string'){
        myId = myinput;
    } else {
        myId = myinput.id; // myinput.id is enough
    }

    // do something

}

or if you really want to check against if it's HTMLElement then every DOM html element extends HTMLElement abstract interface. Check MDC for more info on HTMLElement.

    ...

    if (myinput instanceof HTMLElement){
        myId = myinput.id; // myinput.id is enough
    } else {
        myId = myinput;
    }

    ...

In the end it won't really matter... your call!

Tom

edited Feb 17, 2011 at 20:40

answered Feb 17, 2011 at 20:35

Tom Tu

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2 Comments

fregante Over a year ago

HTMLElement wasn't working for me in some browser (probably IE8) so now I'm checking for nodeType

designcise Over a year ago

You could do $(myinput).length > 0 to see if element exists in the DOM.

user463535 · Accepted Answer · 2011-02-17 20:38:46Z

6

You would implement your function like this:

function myfunction(myinput){

 if (myinput.nodeType){
    var myID = $(myinput).attr('id');
 } else {
    var myID = myinput;
 }

 // Do stuff with myID ...

}

More information about nodeType.

answered Feb 17, 2011 at 20:38

user463535

1 Comment

sma Over a year ago

+1 for this solution. jQuery code uses this in its isPlainObject function to exclude DOM nodes.

Ilia Draznin · Accepted Answer · 2011-02-17 22:03:58Z

0

I wonder if a nice ternary would work, something like this

var myID = $(myInput).attr('id') ? $(myInput).attr('id') : myInput;

answered Feb 17, 2011 at 22:03

Ilia Draznin

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Comments

devzorg · Accepted Answer · 2011-02-17 20:17:21Z

-2

if( myinput instanceof domElement ) alert("Yes");

answered Feb 17, 2011 at 20:17

devzorg

1057 bronze badges

2 Comments

BoltClock Over a year ago

Nope, there's no such class as domElement.

yckart Over a year ago

What you mean is Element or Node ;)

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