Not having much luck with this. I'm trying to determine if a var is not empty.
$('#content').mouseup(function() {
var selection = getSelected();
if (typeof(selection) !=='undefined') {
alert(selection);
}
});
What this is doing is grabbing any text the user has selected -- but it shows an empty alert even if the user just mouseup's on the div.
Just say:
if (selection) {
alert(selection);
}
The simple true/false test in Javascript returns true if the member is defined, non-null, non-false, non-empty string, or non-zero.
Also, in Javascript, something can be equal to a value undefined or actually undefined (meaning, no such named object exists). e.g.
var x = undefined;
alert(x===undefined); /* true; */
alert(x); /* false */
x=1;
alert(x); /* true */
alert(y===undefined); /* reference error - there's nothing called y */
alert(y); /* reference error */
alert(typeof y === "undefined"); /* true */
As the comment below notes, if you are not sure if something even exists at all, you should test that first using typeof.
alert(selection) would cause an error. If you are getting an empty alert box, it's because the value of selection is something that's blank but not an empty string. Maybe it's a single space or something. I have no idea what that function returns, but it's not returning an empty string, or the selection wouldn't show. See: jsfiddle.net/2mm5nYour code is perfectly accurate for detecting an undefined value, which means that the function always returns some kind of value even if there is no selection.
If the function for example returns a selection object (like the window.getSelection function), you check the isCollapsed property to see if the selection is empty:
if (!selection.isCollapsed) ...
you can simply use:
if (selection) {
alert(selection);
}
getSelected()function?