[SOLVED] simple if statement logic error

[The Little Guy]

function isExtGood(id){
var val = document.getElementById(id).value;
var match = /.(jpg|gif|png)/i.exec(val);
if(match[0] != '.jpg' || match[0] != '.gif' || match[0] != '.png'){
	alert("Unsuported file type (.jpg, .gif, OR .png) "+match[0]);
	document.getElementById(id).value = '';
}
}

 

Ok the above function checks a file field and makes sure the file is a jpg, gif, or png file if not it alerts the user and clears the field.

 

The problem is, that it doesn't work... if I place a txt file in the field, it doesn't display the alert, but if I do a jpg, gif, or png it does display the alert, and that is backwards... what is wrong?