match capture groups and return index
npm install match-indexGet index of each capture.
- Get index of each capture in a JavaScript regex - Stack Overflow
- tc39/String.prototype.matchAll: ES Proposal, specs, tests, reference implementation, and polyfill/shim for String.prototype.matchAll
You want to match a regex like /(a.)(b)(c.)d/ with "aabccde", and get the following information back:
"aa" at index = 0
"b" at index = 2
"cc" at index = 3
But, it is difficult to write.
match-index provide matchCaptureGroupAll function that easy to get this information!
``jsMatchCaptureGroup
const text = "aabccde";
const regExp = /(a.)(b)(c.)d/;
const captureGroups = matchCaptureGroupAll(text, regExp);
// array of
assert.equal(captureGroups.length, 3);
const [a, b, c]= captureGroups;
assert.equal(a.text, "aa");
assert.equal(a.index, 0);
assert.equal(b.text, "b");
assert.equal(b.index, 2);
assert.equal(c.text, "cc");
assert.equal(c.index, 3);
npm install match-index
match-index provide two functions
Retrieves the captured matches when matching a string against a regular expression.
Example of matchCaptureGroupAll()
`js`
// get "ABC" and "EFC that are captured by ( and )
const captureGroups = matchCaptureGroupAll("ABC EFG", /(ABC).*?(EFG)/);
// captureGroups is array of MatchAllGroup
/**
* @typedef {Object} MatchAllGroup
* @property {Array} all
* @property {string} input
* @property {number} index
* @property {MatchCaptureGroup[]} captureGroups
*/
assert(captureGroups.length, 2);
const [x, y] = captureGroups;
assert.equal(x.text, "ABC");
assert.equal(x.index, 0);
assert.equal(y.text, "EFG");
assert.equal(y.index, 4);
matchCaptureGroupAll use matchAll in internal.
Retrieves the matches all when matching a string against a regular expression.
Example of matchAll()
`jsMatchAllGroup
const text = 'test1test2';
const regexp = /t(e)(st(\d?))/g;
const captureGroups = matchAll(text, regexp);
// captureGroups is array of
/**
* @typedef {Object} MatchAllGroup
* @property {Array} all
* @property {string} input
* @property {number} index
* @property {MatchCaptureGroup[]} captureGroups
*/
assert.equal(captureGroups.length, 2);
const [test1, test2] = captureGroups;
assert.equal(test1.index, 0);
assert.equal(test1.input, text);
assert.deepEqual(test1.all, ['test1', 'e', 'st1', '1']);
assert.deepEqual(test1.captureGroups, [
{
index: 1,
text: 'e'
}, {
index: 2,
text: 'st1'
}, {
index: -1,// Limitation of capture nest
text: '1'
}
]);
assert.equal(test2.index, 5);
assert.equal(test2.input, text);
assert.deepEqual(test2.all, ['test2', 'e', 'st2', '2']);
assert.deepEqual(test2.captureGroups, [
{
index: 6,
text: 'e'
}, {
index: 7,
text: 'st2'
}, {
index: -1, // Limitation
text: '2'
}
]);
`
matchAll and matchCaptureGroupAll doesn't support nest capture.
e.g.) last captureGroups item's index is wrong result.
(st(\d?)) is nest capture.
`jsMatchAllGroup
const text = 'test1test2';
const regexp = /t(e)(st(\d?))/g;
const captureGroups = matchAll(text, regexp);
// captureGroups is array of
/**
* @typedef {Object} MatchAllGroup
* @property {Array} all
* @property {string} input
* @property {number} index
* @property {MatchCaptureGroup[]} captureGroups
*/
assert.equal(captureGroups.length, 2);
const [test1, test2] = captureGroups;
assert.equal(test1.index, 0);
assert.equal(test1.input, text);
assert.deepEqual(test1.all, ['test1', 'e', 'st1', '1']);
assert.deepEqual(test1.captureGroups, [
{
index: 1,
text: 'e'
}, {
index: 2,
text: 'st1'
}, {
index: -1,// Limitation of capture nest
text: '1'
}
]);
`
Welcome to pull request to fix this limitation :)
npm test
1. Fork it!
2. Create your feature branch: git checkout -b my-new-feature
3. Commit your changes:
4. Push to the branch:
5. Submit a pull request :D
MIT