Javascript get number from string?

Question

I have an array containing strings with prices and sometimes surrounded by characters.

How do I transform it from?

[0] > '$9.99/aa'
[1] > '$2.99'
[2] > '$1.'

to:

[0] > '9.99'
[1] > '2.99'
[2] > '1'

So I can do comparisons with the values? I just need to know how to change one and I can apply it to the array easily

Mike Samuel · Accepted Answer · 2012-01-19T21:50:20.987

2

+myString.replace(/[^\d.ex-]+/gi, '')

strips out all characters that cannot appear in a JavaScript number, and then applies the + operator to it to convert it to a number. If you don't have numbers in hex format or exponential format then you can do without the ex.

EDIT:

To handle locales, and handle numbers in a more tailored way, I would do the following

// Get rid of myriad separators and normalize the fraction separator.
if ((0.5).toLocaleString().indexOf(',') >= 0) {
  myString = myString.replace(/\./g, '').replace(/,/g, '.');
} else {
  myString = myString.replace(/,/g, '');
}

var numericValue = +(myString.match(
    // Matches JavaScript number literals excluding octal.
    /[+-]?(?:(?:(?:0|[1-9]\d*)(?:\.\d*)?|\.\d+)(?:e[+-]?\d+)?|0x[0-9a-f]+)/i)
    // Will produce NaN if there's no match.
    || NaN);

edited Jan 19 '12 at 21:50

answered Jan 18 '12 at 22:02

Mike Samuel

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1

Your regex is quite... broad. – Hello71 Jan 18 '12 at 22:08
+1 the only thing I would add is I don't think this conversion (or any of the float conversions in js) are locale dependent. just an FYI – J. Holmes Jan 18 '12 at 22:10
thanks, I still have a problem though. If the string is: "$1.99." I get "1.99.". Is there an easy solution for this? – lisovaccaro Jan 18 '12 at 22:22
@Hello71, Liso22, you can narrow the regular expression by just looking for the number grammar. I edited it to find valid numbers and to expect locale sensitive fraction separators. – Mike Samuel Jan 18 '12 at 22:39
@32bitkid, I edited it to use `0.5.toLocaleString()` to normalize fraction separators and myriad separators before converting to a number. – Mike Samuel Jan 18 '12 at 22:44
@MikeSamuel: I don't think that works. You may need to use `(0.5).toLocaleString()`. – Hello71 Jan 19 '12 at 21:45
Huh. Apparently not (in Firefox, anyways). – Hello71 Jan 19 '12 at 21:46
@Hello71, it's not required. `0.toLocaleString` won't work because it is tokenized as `0.` followed by `toLocaleString`, but `0.5.toLocaleString` is tokenized as `0.5` then `.` then `toLocaleString`. Edited since it's potentially confusing. – Mike Samuel Jan 19 '12 at 21:50

score 2 · Answer 2 · edited May 23 '17 at 11:51

2

Your case requires a Regular Expression, because all native number-converting methods fail when the string is prefixed by a non-digit/dot.

var string = '$1.22'; //Example
string = string.replace(/[^0-9.]+/g, '');
// string = '1.22'

If you want to convert this string to a digit, afterwards, you can use parseInt, +, 1*.

For a comparison of these number-converting methods, see this answer

edited May 23 '17 at 11:51

Community

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answered Jan 18 '12 at 22:03

Rob W

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score 1 · Answer 3 · answered Jan 18 '12 at 22:12

parseFloat() works for such cases when you need the decimals. The regex will give the matched number for all your cases in the 0 index. Sample code is below.

var one = "2.99";
var two = '$1.';
var three = '$3tees';
var four = '$44.10'    

var regex = /\d+\.?(\d+)?/;
var num = parseFloat(one.match(regex)[0]);

georg · Answer 4 · 2012-01-18T23:38:50.523

1

Strip everything before the first digit and apply parseFloat to the rest:

s = "$9.99/aa"
alert(parseFloat(s.replace(/^\D*/, '')))

edited Jan 18 '12 at 23:38

answered Jan 18 '12 at 22:22

georg

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Hello71 · Answer 5 · 2012-01-18T22:08:22.773

0

The lazy way:

+string;

The proper way:

parseInt(string, 10);

Thus:

for (var i = 0; i < arr.length; i++) {
    var match = /\$(\d*)\.(\d\d)/.exec(arr[i]);
    arr[i] = parseInt(match[1] + match[2]);
}

Edit: Oh, you wanted something more than 10 dollars.

Another edit: Apparently parseInt (at least in my browser) ignores trailing characters. In that case, my original implementation would have worked.

for (var i = 0; i < arr.length; i++) {
    arr[i] = parseInt(arr[i].substring(1));
}

edited Jan 18 '12 at 22:08

answered Jan 18 '12 at 22:01

Hello71

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Read the question more closely. – Rob W Jan 18 '12 at 22:02
1

neither of these work with the data provided. you just read the *title*, didn't you. – J. Holmes Jan 18 '12 at 22:03
@RobW: Are you referring to the loop part or something else? – Hello71 Jan 18 '12 at 22:03

score 0 · Answer 6 · answered Jan 18 '12 at 22:03

0

+/[\d\.]+/.exec('$9.99/aa')[0]

Finds the first group of digits and periods, converting them to a float

answered Jan 18 '12 at 22:03

dorsh

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Javascript get number from string?

6 Answers6