You can just replace every space and comma with space then trim those trailing spaces:

var str=" , this,  is a ,,, test string , , to find regex,,in js.  , ";
res = str.replace(/[, ]+/g, " ").trim();

jsfiddle demo

Answer from Jerry on Stack Overflow
Discussions

[javascript] how to effectively convert string to array while removing commas and the space at the beginning/end if there was any?
Trim after the split with map, so str.split(",").map((s) => s.trim()) Much easier to read than regex imo More on reddit.com
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September 14, 2021
How to remove all commas from a string and add white space?
I need to be able to remove ALL commas from those strings and keep the white space in order to have: var resultA = "November 5 1916"; var resultB = "October 5–10 1592"; ... I do need the split() afterwards as I need each string in an array. ... I'm no js expert, but your calls to replace ... More on stackoverflow.com
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Removing commas in a string
Hey guys, i have a basic js question here… how can i remove commas in a string and replace them with a space. let myString = 'hello,this,is,a,difficult,to,read,sentence'; More on forum.freecodecamp.org
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September 18, 2019
Remove commas from the string using JavaScript - Stack Overflow
I want to remove commas from the string and calculate those amount using JavaScript. For example, I have those two values: 100,000.00 500,000.00 Now I want to remove commas from those string an... More on stackoverflow.com
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Reactgo
reactgo.com › home › how to remove commas from a string in javascript
How to remove commas from a string in JavaScript | Reactgo
August 16, 2021 - To remove the commas from a string, we can use the replace() method in JavaScript.
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Reddit
reddit.com › r/webdev › [javascript] how to effectively convert string to array while removing commas and the space at the beginning/end if there was any?
r/webdev on Reddit: [javascript] how to effectively convert string to array while removing commas and the space at the beginning/end if there was any?
September 14, 2021 -

i think this can be done by regEx by i don't how to look it up.

this is a learning project, but i am just thinking about the scale

i have a form where the user enter a bunch of categories and i want the user to separate those categories with a comma, but working on the case where the user add the comma but also a space after the comma (as we all do) or before the comma, how to go about treating this case, because i don't want to end up with two or three categories that are the same.

edit: i did it but i don't want to remove the post to help anyone with the same issue.

here's what i did

const categoriesAsString = e.target.value;

const categoriesTrimmed = categoriesAsString.trim();

const categoriesAsStringWithWhiteSpace = categoriesTrimmed.replace(/\s*,\s*/g,",");

const categoriesAsArray = categoriesAsStringWithWhiteSpace.split(",");

setCategories(categoriesAsArray);

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Medium
frontendinterviewquestions.medium.com › how-to-remove-comma-from-string-in-javascript-0b5cc90fd65f
How to remove comma from string in JavaScript | by Pravin M | Medium
April 15, 2024 - The most straightforward approach to remove commas from a string in JavaScript is by using the replace method along with a regular expression.
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TutorialsPoint
tutorialspoint.com › split-the-sentences-by-comma-and-remove-surrounding-spaces-javascript
Split Space Delimited String and Trim Extra Commas and Spaces in JavaScript?
October 3, 2020 - Messy string: ,,, Hello ,,, World ,,, Cleaned string: Hello World · Using split(/[\s,]+/).join() is an efficient way to remove multiple consecutive commas and spaces from strings.
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Bobby Hadz
bobbyhadz.com › blog › javascript-remove-all-commas-from-string
Remove/Replace all Commas from a String in JavaScript | bobbyhadz
Use the `String.replaceAll()` method with a comma as the first parameter and an empty string as the second to remove all commas from a string.
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Pluralsight
pluralsight.com › blog › tech guides & tutorials
Render a String with Non-breaking Spaces in React | Pluralsight
June 14, 2020 - Create a simple JSX template with an input field for the user to enter the string and a Format String button. When the user clicks the Format String button, display the formatted string, i.e., the string without any empty spaces on the DOM. ...
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freeCodeCamp
forum.freecodecamp.org › javascript
Removing commas in a string - Programming
September 18, 2019 - Hey guys, i have a basic js question here… how can i remove commas in a string and replace them with a space. let myString = 'hello,this,is,a,difficult,to,read,sentence';
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CoreUI
coreui.io › answers › how-to-trim-whitespace-from-a-string-in-javascript
How to trim whitespace from a string in JavaScript · CoreUI
May 19, 2026 - The replace(/\s+/g, ' ').trim() pattern is extremely common in production code. It normalizes any sequence of whitespace characters into a single space and then removes the edges.
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Java2Blog
java2blog.com › home › core java › remove comma from string in javascript
Remove Comma from String in JavaScript - Java2Blog
May 24, 2022 - Replacement String – String with which we want to replace matched string. Let’s go through regular expression /\,/g used in above replace method. The forward slashes mark start and end of regular expression · We have used \ before , to escape it as , has special meaning in regular expression. g denotes global replacement here. It is flag at end of regex which depicts that we want to remove all the commas not only first one.
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To remove the commas, you'll need to use replace on the string. To convert to a float so you can do the maths, you'll need parseFloat:

var total = parseFloat('100,000.00'.replace(/,/g, '')) +
            parseFloat('500,000.00'.replace(/,/g, ''));
2 of 3
7

Related answer, but if you want to run clean up a user inputting values into a form, here's what you can do:

const numFormatter = new Intl.NumberFormat('en-US', {
  style: "decimal",
  maximumFractionDigits: 2
})

// Good Inputs
parseFloat(numFormatter.format('1234').replace(/,/g,"")) // 1234
parseFloat(numFormatter.format('123').replace(/,/g,"")) // 123

// 3rd decimal place rounds to nearest
parseFloat(numFormatter.format('1234.233').replace(/,/g,"")); // 1234.23
parseFloat(numFormatter.format('1234.239').replace(/,/g,"")); // 1234.24

// Bad Inputs
parseFloat(numFormatter.format('1234.233a').replace(/,/g,"")); // NaN
parseFloat(numFormatter.format('$1234.23').replace(/,/g,"")); // NaN

// Edge Cases
parseFloat(numFormatter.format(true).replace(/,/g,"")) // 1
parseFloat(numFormatter.format(false).replace(/,/g,"")) // 0
parseFloat(numFormatter.format(NaN).replace(/,/g,"")) // NaN

Use the international date local via format. This cleans up any bad inputs, if there is one it returns a string of NaN you can check for. There's no way currently of removing commas as part of the locale (as of 10/12/19), so you can use a regex command to remove commas using replace.

ParseFloat converts the this type definition from string to number

If you use React, this is what your calculate function could look like:

updateCalculationInput = (e) => {
    let value;
    value = numFormatter.format(e.target.value); // 123,456.78 - 3rd decimal rounds to nearest number as expected
    if(value === 'NaN') return; // locale returns string of NaN if fail
    value = value.replace(/,/g, ""); // remove commas
    value = parseFloat(value); // now parse to float should always be clean input

    // Do the actual math and setState calls here
}
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Bobby Hadz
bobbyhadz.com › blog › javascript-add-space-after-each-comma-string
Add Space after each Comma in a String using JavaScript | bobbyhadz
March 4, 2024 - In its entirety, the regular expression matches every capital letter in the string and replaces it with a space and then the capital letter. The last step is to use the String.trim() method to remove the leading and trailing spaces from the ...
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Stack Abuse
stackabuse.com › how-to-trim-whitespacescharacters-from-a-string-in-javascript
How to Trim Whitespaces/Characters from a String in JavaScript
May 22, 2023 - In this guide, learn how to trim the whitespaces at the start and end of a string in JavaScript with built-in methods and Regular Expressions. We'll use the `trim()`, `trimStart()`, `trimEnd()`, `substr()` and `replace()` methods.
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GeeksforGeeks
geeksforgeeks.org › how-to-remove-spaces-from-a-string-using-javascript
How to Remove Spaces From a String using JavaScript? | GeeksforGeeks
JavaScript string.replace() method is used to replace a substring. With Regular expressions pattern we can find all spaces (/\s/g) and globally replace all space occurrences with an empty string.
Published   November 14, 2024
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TutorialsPoint
tutorialspoint.com › article › how-to-trim-white-spaces-from-input-in-reactjs
How to Trim White Spaces from input in ReactJS?
March 15, 2026 - function customTrim(str) { // Split by spaces and filter out empty strings from start/end let words = str.split(' '); // Remove empty strings from beginning while (words.length > 0 && words[0] === '') { words.shift(); } // Remove empty strings ...