How to check "#" tag is there or not in a string?

Question

I'm a beginner in node.js so please do excuse me if my question is foolish. As we know we can use

var regex = /[ !@#$%^&*()_+\-=\[\]{};':"\\|,.<>\/?]/g;
regex.test(str);

to check whether a string contains special charecters or not .But what I'm asking is how to check for only a particular charecter means how can I check only presence of #.

I tried to do var regex = /[#]/g; regex.test(str). Although it's not working but are there any other method of doing this?

That's overkill. Just use [`indexOf`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/indexOf) — Federico klez Culloca, Mar 13 '18 at 14:20
`But it's not working.` In what way.. `/[#]/g.test("hello#")` return true for me. — Keith, Mar 13 '18 at 14:26

score 5 · Answer 1 · answered Mar 13 '18 at 14:22

5

You don't need a regex to find a single character in a string. You can use indexOf, like this:

var hasHashtag = str.indexOf('#') >= 0;

This returns true if the character is in the string.

answered Mar 13 '18 at 14:22

Federico klez Culloca

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score 4 · Accepted Answer · answered Mar 13 '18 at 14:21

4

Use includes to check the existence of # in your string. You don't actually require regex to do that.

var str = 'someSt#ring';
var res = str.includes('#');
console.log(res);

str = 'someSt#ri#ng';
res = str.includes('#');
console.log(res);

str = 'someString';
res = str.includes('#');
console.log(res);

answered Mar 13 '18 at 14:21

Ankit Agarwal

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note that it does not work in IE. – keja Mar 13 '18 at 14:24
The Polyfill for `.includes` uses `.indexOf` anyways, so for now, sadly, `.indexOf` might be safer to use – wjvander Mar 13 '18 at 14:25
1

the post is tagged `node.js` anyway, so I'd say the point is moot – Federico klez Culloca Mar 13 '18 at 14:26
`includes` give you a Boolean value so I prefer that to use instead of `indexOf` as according to this situation OP will most likely use `if-else` on this condition. – Ankit Agarwal Mar 13 '18 at 14:27
@keja yes it will not work in IE but will work on Edge. – Ankit Agarwal Mar 13 '18 at 14:28
@keja Unless stipulated, answer on SO really should be targeting modern browsers anyway. Any serious JS programmers toolchain should be pollyfill & transpiler capable. – Keith Mar 13 '18 at 14:35
i agree, also the reason i upvoted this as well as added the comment. – keja Mar 13 '18 at 14:50

score 2 · Answer 3 · answered Mar 13 '18 at 14:23

2

Use indexOf

str.indexOf('#') >= 0;

answered Mar 13 '18 at 14:23

phuzi

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How to check "#" tag is there or not in a string?

3 Answers3