Question 191278 in Javascript Question posted in
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Javascript – Regex to find specific key value pairs

I have a list of strings

time:1001 name:foo avg:5.7
time:1002 
time:1003 avg:1.2
time:1004 name:f 
time:1005 name:bar avg:2.1

I want to pick out the strings which match time:value name:value avg:value exactly and extract

[time, 1001], [name, foo], [avg, 5.7]
[time, 1005], [name, bar], [avg, 2.1]

using regex: /(w+):s*(?:"([^"]*)"|(S+))/g

code:

const regex = /(w+):s*(?:"([^"]*)"|(S+))/g;
let match = regex.exec(line);

I get all the lines,

[time, 1001], [name, foo], [avg, 5.7]
[time:1002], [name:undefined], [avg, undefined]
[time:1003], [name:undefined], [avg:1.2]
[time:1004], [name:f], [avg, undefined]
[time, 1005], [name, bar], [avg, 2.1]

how do I select the ones with all key values present

Tags:

3

Answers


  1. 0

    You can create your regexp dynamically to use capture groups:

    const str = `time:1001 name:foo avg:5.7
time:1002 
time:1003 avg:1.2
time:1004 name:f 
time:1005 name:bar avg:2.1`;

const result = [];

const regex = new RegExp('(\w+):([^\s]+)(?:[^\n]|$)'.repeat(3), 'g');
let m;
while (m = regex.exec(str)) {
    result.push(m.slice(1).reduce(
        (arr, item, idx) => (arr[Math.floor(idx / 2)] ??=[]).push(item) && arr
        , []
    ));
}

console.log(JSON.stringify(result));

    Or use {3} to tell that you want exactly 3 key:value pairs in a
    line and parse a line manually:

    const str = `time:1001 name:foo avg:5.7
time:1002 
time:1003 avg:1.2
time:1004 name:f 
time:1005 name:bar avg:2.1`;

const result = str.match(/(w+:[^s]+[^n]*){3}/g).map(line => 
  line.split(/s+/g).map(item => item.split(':'))
);

console.log(JSON.stringify(result));
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  2. 0

    Make your regexp match the keys exactly, instead of using w+ to match anything.

    const lines = [
  'time:1001 name:foo avg:5.7 ',
  'time:1002 ',
  'time:1003 avg:1.2 ',
  'time:1004 name:f  ',
  'time:1005 name:bar avg:2.1 ',
];

const regex = /time:(d+)s+name:(w+)s+avg:([d.]+)/;

result = [];
lines.forEach(line => {
  m = line.match(regex);
  if (m) {
    result.push([
      ['time', m[1]],
      ['name', m[2]],
      ['avg', m[3]]
    ]);
  }
});

console.log(result);
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  3. 0

    One possible approach, which consumes the data-blob entirely as is …

    time:1001 name:foo avg:5.7
time:1002 
time:1003 avg:1.2
time:1004 name:f 
time:1005 name:bar avg:2.1

    … could be based on a globally flagged regex like …

    /times*:s*(?<time>S+)s*names*:s*(?<name>S+)s*avgs*:s*(?<avg>S+)/g

    … which utilizes named capturing groups and gets applied via matchAll.

    Since the resulting iterator’s array-representation features just the valid matches, one can map said array, where with each iteration step one does render a valid part of the final result via e.g. a template literal. The mapped array then just needs to be joined with a newline / 'n'.

    The next provided executable example code generates exactly the result the OP was asking for, thus proving all of the above said/explained …

    const sampleData =
`time:1001 name:foo avg:5.7
time:1002 
time:1003 avg:1.2
time:1004 name:f 
time:1005 name:bar avg:2.1`;

const regXCapture =
  // see ... [https://regex101.com/r/hoiUFH/1]
  /times*:s*(?<time>S+)s*names*:s*(?<name>S+)s*avgs*:s*(?<avg>S+)/g;

console.log(
  [...sampleData.matchAll(regXCapture)]
    .map(({ groups: { time, name, avg } }) =>
      `[time, ${ time }], [name, ${ name }], [avg, ${ avg }]`
    )
    .join('n')
);
    .as-console-wrapper { min-height: 100%!important; top: 0; }
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