groups-object-unmatched.js

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// Copyright 2017 the V8 project authors. All rights reserved.

// This code is governed by the BSD license found in the LICENSE file.

/*---

description: >

  Test the groups object with matched and unmatched named captures.

esid: sec-regexpbuiltinexec

features: [regexp-named-groups]

info: |

  Runtime Semantics: RegExpBuiltinExec ( R, S )

    24. If _R_ contains any |GroupName|, then

      a. Let _groups_ be ObjectCreate(*null*).

    25. Else,

      a. Let _groups_ be *undefined*.

    26. Perform ! CreateDataProperty(_A_, `"groups"`, _groups_).

---*/

const re = /(?<a>a).|(?<x>x)/;

const result = re.exec("ab");

assert.sameValue(Object.getPrototypeOf(result), Array.prototype);

assert(result.hasOwnProperty("groups"));

assert.sameValue("ab", result[0]);

assert.sameValue("a", result[1]);

assert.sameValue(undefined, result[2]);

assert.sameValue(0, result.index);

assert.sameValue("a", result.groups.a);

assert.sameValue(undefined, result.groups.x);

// `a` is a matched named capture, `b` is an unmatched named capture, and `z`

// is not a named capture.

Array.prototype.groups = { a: "b", x: "y", z: "z" };

assert.sameValue("a", "ab".replace(re, "$<a>"));

assert.sameValue("", "ab".replace(re, "$<x>"));

assert.sameValue("", "ab".replace(re, "$<z>"));

Array.prototype.groups = undefined;

reportCompare(0, 0);