Creating a regular expression to capture a numerical value enclosed by different characters:

Question

Creating a regular expression to capture a numerical value enclosed by different characters:

export interface ValueParserResult {
  value: number, 
  error: string
}

interface subParseResult {
  result: (string | number) [], 
  error: string
}

class ValueParser {

  parse(eq: string, values: {[key: string] : number}, level?: number) : ValueParserResult {
    const result: ValueParserResult = { value: 0, error: "" }
  
    const numberRe: RegExp = /([^|\\(||/|/\\-|-|\\*|\\*\\-|+|\\^])+([0-9.]*)([$|(|)|/|/-|-|*|*-|+|])+/g;
          
    const eqParse = eq.split(" ").join('');
    eqParse.replace(numberRe, (matched) => {
      return " ," + matched;
    })
    
    console.log(eqParse)
    return result;

  }
}

const vp = new ValueParser();
const values = {x: 18, y:-3, z: 7}

const eq = "3452/132*67*(x+y/z)"

vp.parse(eq, values)

This snippet formats the eqParse data by adding a space and comma before each value instead of capturing surrounding strings.

javascript regex typescript

Answer 1

Answer №1

There seems to be some confusion here:

The pipe | is not functioning as an OR-operator within the [ ] class, and you cannot match a sequence of multiple characters (like /-) in that type of regex class. Each character inside the [ ] is treated individually, and the class matches only one of them.
The replace method does not alter the original string it operates on. Also, strings are immutable in JavaScript. Therefore, you need to store the result of this operation in a new variable.

Below is the corrected section of your code:

const eq = "123/456*82*(a+b/c)";
// A regex pattern that can match alphanumerics (including periods) or non-alphanumerics:
const numberRe = /[\w.]+|[^\w.]+/g
// Assign the return value of the replace call to eqParse:
const eqParse = eq.replace(/ /g, "").replace(numberRe, (matched) => {
  return ", " + matched; // Did you mean to add a comma first?
}).slice(2); // Skip the first ", "

console.log(eqParse);

Answer 2

There seems to be some confusion here:

The pipe | is not functioning as an OR-operator within the [ ] class, and you cannot match a sequence of multiple characters (like /-) in that type of regex class. Each character inside the [ ] is treated individually, and the class matches only one of them.
The replace method does not alter the original string it operates on. Also, strings are immutable in JavaScript. Therefore, you need to store the result of this operation in a new variable.

Below is the corrected section of your code:

const eq = "123/456*82*(a+b/c)";
// A regex pattern that can match alphanumerics (including periods) or non-alphanumerics:
const numberRe = /[\w.]+|[^\w.]+/g
// Assign the return value of the replace call to eqParse:
const eqParse = eq.replace(/ /g, "").replace(numberRe, (matched) => {
  return ", " + matched; // Did you mean to add a comma first?
}).slice(2); // Skip the first ", "

console.log(eqParse);

Answer 3

Answer №2

Updated regex pattern to extract numbers surrounded by other characters as shown below

const numberRe: RegExp = /(?<=[^\d.])\d+(?:\.\d+)?(?=[^\d.])/g;

I (geewhizbang) made a revision and shared it on a typescript playground:

Answer 4

Updated regex pattern to extract numbers surrounded by other characters as shown below

const numberRe: RegExp = /(?<=[^\d.])\d+(?:\.\d+)?(?=[^\d.])/g;

I (geewhizbang) made a revision and shared it on a typescript playground:

Creating a regular expression to capture a numerical value enclosed by different characters:

Answer №1

Answer №2

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