Javascript Remove all charater except leading - , one dot and digits

Question

First of all this question is not same as

strip non-numeric characters from string or

Regex to replace everything except numbers and a decimal point

I want to convert a string with valid number like.

--1234// will be -1234
-123-123 will be -123123
12.123.3 will be 12.1233
-123.13.123 will be -123.13123

I tried those

number.replace(/[^0-9.-]/g, '') //it accepts multiple . and -
number.replace(/[^0-9.]-/g, '').replace(/(\..*)\./g, '$1');//it accepts multiple minus

I am facing Problem with leading minus sign.

How I can convert a string which will remove all characters except leading -(remove other minus),digits and only one dot(remove other dots)

I don't think you can do this with regex, you are applying logic to your matches. For instance, you want to concatenate different groups of numbers into one discarding some characters in the middle. Regex is not the tool for doing this. — Federico Piazza, Mar 30 '16 at 23:34
@FedericoPiazza I am almost there.Can you help me to write the regex to find all -(minus sign) except first one. — Shaiful Islam, Mar 30 '16 at 23:40
@ShaifulIslam: I came up with solution to solve the -(minus sign) problem. But `.(decimal)` position cannot be defined by simple rule. Check my answer for explanation. — , Mar 30 '16 at 23:42

score 7 · Accepted Answer · edited Jun 20 '20 at 09:12

7

Here I am sharing my solution.
Lets assume the string is a;

//this will convert a to positive integer number
b=a.replace(/[^0-9]/g, '');

//this will convert a to integer number(positive and negative)
b=a.replace(/[^0-9-]/g, '').replace(/(?!^)-/g, '');

//this will convert a to positive float number

b=a.replace(/[^0-9.]/g, '').replace(/(..*)./g, '$1');

//this will convert a to float number (positive and negative)

b=a.replace(/[^0-9.-]/g, '').replace(/(..*)./g, '$1').replace(/(?!^)-/g, '');

Update for floating number.(solves copy paste problem)

//For positive float number
b=a.replace(/[^0-9.]/g, '').replace('.', 'x').replace(/\./g,'').replace('x','.');

//For Negative float number
b=a.replace(/[^0-9.-]/g, '').replace('.', 'x').replace(/\./g,'').replace('x','.').replace(/(?!^)-/g, '');

edited Jun 20 '20 at 09:12

Community

1
1

answered Apr 28 '17 at 01:29

Shaiful Islam

7,034
12
38
58

Last one converts `'1.2.3.4.5'` to `"1.2.3.45"` – Atomosk Dec 07 '19 at 04:23
@Atomosk thanks for the example. However I use that expression in input field.When user type one dot they cannot type 2nd dot for that expression,that's why I did not notice that exception. – Shaiful Islam Dec 15 '19 at 23:01
What about copying and pasting? – Atomosk Dec 23 '19 at 06:15

score 6 · Answer 2 · answered Nov 06 '18 at 09:47

6

Based on @Shaiful Islam's answer, I added one more code.

var value = number
    .replace(/[^0-9.-]/g, '')       // remove chars except number, hyphen, point. 
    .replace(/(\..*)\./g, '$1')     // remove multiple points.
    .replace(/(?!^)-/g, '')         // remove middle hyphen.
    .replace(/^0+(\d)/gm, '$1');    // remove multiple leading zeros. <-- I added this.

Result

00.434 => 0.434

answered Nov 06 '18 at 09:47

wonsuc

3,498
1
27
30

1

It doesn't remove multiple dots. – Jsowa Jan 08 '21 at 09:37

score 3 · Answer 3 · answered Mar 30 '16 at 23:55

3

Not very clean, but works!

var strings = ["-1234","-123-123","12.123.3", "-123.13.123"];
strings.forEach(function(s) {
    var i = 0;
    s = s.replace(/(?!^)-/g, '').replace(/\./g, function(match) { 
        return match === "." ? (i++ === 0 ? '.' : '') : ''; 
    });
    console.log(s);
});

answered Mar 30 '16 at 23:55

hallucinations

3,424
2
16
23

Thanks I got Idea from your answer `number.replace(/[^0-9.-]/g, '').replace(/(\..*)\./g, '$1').replace(/(?!^)-/g, '');` – Shaiful Islam Mar 31 '16 at 00:08
@ShaifulIslam, glad I could help. Would appreciate if you could accept the answer. – hallucinations Mar 31 '16 at 00:19

score 0 · Answer 4 · 2016-03-30T23:56:16.333

0

In your sample data given below,

--1234
-123-123
12.123.3
-123.13.123

-(minus sign or hyphen) causes no problem because it's place is only before digits and not between digits. So this can be solved using following regex.

Regex: -(?=-)|(?<=\d)-(?=\d+(-\d+)?$) and replace with empty string.

Regex101 Demo

However, the position of .(decimal) cannot be determined. Because 123.13.123 could also mean 123.13123 and 12313.123.

edited Mar 30 '16 at 23:56

answered Mar 30 '16 at 23:41

Nice but does not work if a minus is added at the end – Donovan Charpin Jan 03 '19 at 19:20

score 0 · Answer 5 · 2016-03-31T00:18:45.723

Without regex, you can map over the characters this way:

// this function takes in one string and return one integer
f=s=>(
    o='',                   // stands for (o)utput
    d=m=p=0,                // flags for: (d)igit, (m)inus, (p)oint
    [...s].map(x=>          // for each (x)char in (s)tring
        x>='0'&x<='9'?      // if is number
            o+=x            // add to `o`
        :x=='-'?            // else if is minus
            m||(p=0,m=o=x)  // only if is the first, reset: o='-';
        :x=='.'?            // else if is point
            p||(p=o+=x)     // add only if is the first point after the first minus
        :0),                // else do nothing
    +o                      // return parseInt(output);
);

['--1234','-123-123','12.123.3','-123.13.123'].forEach(
x=>document.body.innerHTML+='<pre>f(\''+x+'\') -> '+f(x)+'</pre>')

Hope it helps.

In my favor, I can argue my function runs in `O(n)` – Mar 31 '16 at 00:11 — , Mar 31 '16 at 00:11

score 0 · Answer 6 · answered Jan 08 '21 at 09:40

0

My solution:

number.replace(/[^\d|.-]/g, '') //removes all character except of digits, dot and hypen
      .replace(/(?!^)-/g, '') //removes every hypen except of first position
      .replace(/(\.){2,}/g, '$1') //removes every multiplied dot

It should then formatted to the proper locale setting using Intl.NumberFormat.

answered Jan 08 '21 at 09:40

Jsowa

9,104
5
56
60

how about multiple dots?1.2.3 – Shaiful Islam Jan 15 '21 at 19:38
It doesn't work, because there is no info which dot is decimal separator. – Jsowa Jan 15 '21 at 20:54

Javascript Remove all charater except leading - , one dot and digits

6 Answers6

Update for floating number.(solves copy paste problem)