I always (thing != undefined || thing != null)?...:...; check. Is there any method will return bool after this check in javascript or jquery ?
And how would you add this check in jquery as a function?
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4 Answers
if (thing)
{
//your code
}
Is that what you are looking for?
6 Comments
uzay95
:) this is really very easy isn't it :D
Joel Coehoorn
Be careful - this string and maybe a few others will fail that check:
"0".
femseks
He didnt ask for "0" and "false", but undefined or null.
SLaks
@Joel: Wrong. All non-empty strings are truthy.
Ivo Wetzel
@SLaks But only when no comparison is involved, so
if("0") will be true but if("0" == true) won't, since type conversion took place. |
In Javascript, the values null, undefined, "", 0, NaN, and false are all "falsy" and will fail a conditional.
All other values are "truthy" and will pass a conditional.
Therefore, you can simply write thing ? ... : ....
Comments
Try this
function SringisEmpty(str) {
str=str.trim();
return (!str || 0 === str.length);
}
Comments
As the others here have mentioned, several things evaluate as "falsy" that you might not want to (such as empty strings or zero). The simplest way I've found in JavaScript to check for both null and undefined in one statement is:
thing != null
This is using type coercion (double equals instead of triple equals), so undefined values are coerced to null here, while empty strings, zero, etc. do not.
