async-gen-decl-dstr-array-rest-nested-obj-undefined-own.js (1881B)
1 // |reftest| async 2 // This file was procedurally generated from the following sources: 3 // - src/dstr-assignment-for-await/array-rest-nested-obj-undefined-own.case 4 // - src/dstr-assignment-for-await/default/async-gen-decl.template 5 /*--- 6 description: When DestructuringAssignmentTarget is an array literal and the iterable emits `undefined` as the only value, an array with a single `undefined` element should be used as the value of the nested DestructuringAssignment. (for-await-of statement in an async generator declaration) 7 esid: sec-for-in-and-for-of-statements-runtime-semantics-labelledevaluation 8 features: [destructuring-binding, async-iteration] 9 flags: [generated, async] 10 info: | 11 IterationStatement : 12 for await ( LeftHandSideExpression of AssignmentExpression ) Statement 13 14 1. Let keyResult be the result of performing ? ForIn/OfHeadEvaluation(« », 15 AssignmentExpression, iterate). 16 2. Return ? ForIn/OfBodyEvaluation(LeftHandSideExpression, Statement, 17 keyResult, assignment, labelSet). 18 19 13.7.5.13 Runtime Semantics: ForIn/OfBodyEvaluation 20 21 [...] 22 5. If destructuring is true and if lhsKind is assignment, then 23 a. Assert: lhs is a LeftHandSideExpression. 24 b. Let assignmentPattern be the parse of the source text corresponding to 25 lhs using AssignmentPattern as the goal symbol. 26 [...] 27 ---*/ 28 let x = null; 29 // Use the the top-level lexical scope for 'length' to provide compatibility with browsers 30 // where length and name are properties of WindowProxy 31 let length; 32 33 let iterCount = 0; 34 async function * fn() { 35 for await ([...{ 0: x, length }] of [[undefined]]) { 36 assert.sameValue(x, undefined); 37 assert.sameValue(length, 1); 38 39 iterCount += 1; 40 } 41 } 42 43 let promise = fn().next(); 44 45 promise 46 .then(() => assert.sameValue(iterCount, 1, 'iteration occurred as expected'), $DONE) 47 .then($DONE, $DONE);