Does Javascript or jQuery have sometime like the "in" statement in Python?
"a" in "dea" -> True
Googling for the word in is hopeless :(
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5 Answers
It does have an in operator but is restricted to object keys only:
var object = {
a: "foo",
b: "bar"
};
// print ab
for (var key in object) {
print(key);
}
And you may also use it for checks like this one:
if ("a" in object) {
print("Object has a property named a");
}
For string checking though you need to use the indexOf() method:
if ("abc".indexOf("a") > -1) {
print("Exists");
}
4 Comments
peirix
Why was this downvoted? It's the only answer that actually answers the question..?
Matt Grande
The question is about finding a string within a string.
peirix
Aha. I don't know Python, so I read the question to be about the
in statement in javascript. Makes sense now.
Ionuț G. Stan
@Matt Grande, that doesn't mean we shouldn't tell him about the in operator.
you would need to use indexOf
e.g
"dea".indexOf("a"); will return 2
If its not in the item then it will return -1
I think thats what you are after.
Comments
Sounds like you need regular expressions!
if ("dea".match(/a/))
{
return true;
}
4 Comments
Quentin
That's using a sledgehammer to put up a picture hook. Use indexOf.
NickFitz
"dea".test(/a) is more efficient in that context as it just returns true or false directly, eliminating the overhead of constructing a match object and then working out if it's null or not to derive true or false before throwing it away.
NickFitz
Also, what @DavidDorward said ;-)
Matt Grande
Good to know about the test method, thanks. Also, is indexOf noticeably faster than RegEx in this case? I find matching true/false easier to read than checking if it's greater than -1.
How about indexOf?
Comments
With the indexOf function, you can extend the String like such:
String.prototype.in = function (exp) {
return exp.indexOf(this) >= 0;
}
if ("ab".in("abcde")) { //true
}
4 Comments
Matt Grande
And people accused ME of using a sledgehammer to put up a picture hook... :P
Andreas Grech
haha well I still used indexOf, not regExp ;P ...i just made it easier to use
Ionuț G. Stan
I'd rather make a String.prototype.contains(substring) method. Anyway, nice idea.
Andreas Grech
I used "in" to conform to the OP's original request