Javascript remove string from array

Question

I have array:

var data = [];
data.genre = [ 'AAAA', '2', 'CCCc', '3', 'dDdDD' ];

a need to remove all string from array and return only numbers...so above return i need to be:

data.genre = [ '2', '3' ];

I try with this:

alert(data.genre.map(function(x){ return x.replace(/^\d+\.\s*/,"") }));

But nothing is changed...so i need to make whole array remove strings and leave only numbers...this i need to get id with this numbers in my mysql left join genre on id.

You should be using [`filter`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter) not `map.` — Hunter McMillen, Jun 30 '17 at 19:29
Can this be used as regex or somthing familiar? that removes string — John, Jun 30 '17 at 19:30

Patrick Roberts · Answer 1 · 2017-06-30T20:12:38.230

Use Array#filter():

var data = {};
data.genre = [ 'AAAA', '2', 'CCCc', '3', 'dDdDD', '', ' ' ];

data.genre = data.genre.filter(function (str) {
  return str.trim() && !isNaN(str);
});

console.log(data.genre);

This method uses the global function isNaN() to determine if the string can be coerced to a numerical value. If not, isNaN() returns true so we must negate ! that, in order to filter numeric strings. In addition, it preflights this check with String#trim(), and empty strings evaluated as a Boolean are falsy, so strings with whitespace only shall not pass.

Another comment, make sure that you declare data as an object {} instead of an array [] if you're going to assign it arbitrary properties. Arrays are used for storing ordered data.

Nina Scholz · Accepted Answer · 2017-06-30T19:38:07.140

4

You could filter with a regular expression which test for digits only.

var data = {};
data.genre = [ 'AAAA', '2', 'CCCc', '3', 'dDdDD' ];

data.genre = data.genre.filter(function (a) {
    return /^\d+$/.test(a);
});

console.log(data);

edited Jun 30 '17 at 19:38

answered Jun 30 '17 at 19:29

Nina Scholz

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1

the former version was better, why did you make it more complex ? – 0.sh Jun 30 '17 at 19:37
1

Instead of that insanity, why not `.filter(//.test, /^\d+$/)`? – Jun 30 '17 at 19:38
1

ok, you get the old version back. – Nina Scholz Jun 30 '17 at 19:39
@torazaburo no the present edit is better. At least consider the OP, he should be able to know how the code works – 0.sh Jun 30 '17 at 19:39
1

@torazaburo now I wish I could undo my upvote on your comment. That's a comment, not a regular expression, and `RegExp.prototype.test` is better anyway because it does not create an unused variable. – Patrick Roberts Jun 30 '17 at 19:40
1

@torazaburo, that ivokes others who do not like to misuse thisArg. – Nina Scholz Jun 30 '17 at 19:40
2

@torazaburo actually `//.test` makes a comment. – Nina Scholz Jun 30 '17 at 19:41
You're right, although it worked when typed directly into the console. So make it `/./` like you did. – Jun 30 '17 at 19:49
@torazaburo you should write your own answer if you prefer it that way. – Patrick Roberts Jun 30 '17 at 19:50
Well, this whole answer is flawed anyway, since it won't handle `"1.2"`, or `"2e0"`, which we might assume the OP wants to keep. – Jun 30 '17 at 19:51
There's no indication of that. Since it wasn't specified, this is a perfectly valid answer. – Patrick Roberts Jun 30 '17 at 19:52
Wouldn't `!/\D/.test(a)` be cleaner? – Jun 30 '17 at 20:03

score 1 · Answer 3 · answered Jun 30 '17 at 19:30

1

You can use Array.prototype.filter for this. Array.filter takes in a callback function which should return true or false and will composite a new array based on the true/false outputs.

answered Jun 30 '17 at 19:30

Jrs.b

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Javascript remove string from array

3 Answers3