Question 190110 in Javascript Question posted in
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JavaScript RegEx : Extract the first matched value from a Multiline Text

Well, I’ve a Multiline Text like below. I want to extract the first Matched Content value (Here, 10) after Messi: using JavaScript Regular Expressions. The Matching String (Messi: ) Can be on any line.

Neymar: 11
Messi: 10
Ronaldo: 7
Chhetri: 11
Messi: 18

–Thanks In Advance.

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3

Answers


  1. 0

    You can use the following pattern.

    /Messi: (.+?)$/m

    The $ will match the end of the line, so this will capture everything up to it.

    Example

    var string = `Neymar: 11
Messi: 10
Ronaldo: 7
Chhetri: 11
Messi: 18`

var matches = string.match(/Messi: (.+?)$/m)

console.log(matches[1])
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  2. 0

    This function finds the value of a key of choice:

    const input = `Neymar: 11
Messi: 10
Ronaldo: 7
Chhetri: 11
Messi: 18`

function findValue(str, key) {
  const regex = new RegExp('\b' + key + ': ([^\n]*)');
  const matches = str.match(regex);
  return matches ? matches[1] : null;
}

let value = findValue(input, 'Messi');
console.log('Messi =>', value);

value = findValue(input, 'Foo');
console.log('Foo =>', value);

    Output:

    Messi => 10
Foo => null

    Explanation of regex constructor:

    • '\b' — word boundary
    • + key + — dynamically concatenate key
    • ': ([^\n]*)' — expect a colon, a space, and capture everything after that up to the next newline
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  3. 0

    wouldn’t it be better to parse this string once into some data-structure and then use that instead of messing around with regexes.

    const str = `
Neymar: 11
Messi: 10
Ronaldo: 7
Chhetri: 11
Messi: 18
`;

const data = Object.fromEntries(
  str.split("n") // get rows
    .filter(v => v.trim()) // remove empty rows
    .map(row => { // parse row
      const [k, v] = row.split(":", 2);
      return [k.trim(), parseFloat(v)]
    })
);

console.log("data", data);
console.log("data.Messi", data["Messi"]);
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