coerce-symbol-to-prim-invocation.js (1448B)
1 // Copyright (C) 2015 the V8 project authors. All rights reserved. 2 // This code is governed by the BSD license found in the LICENSE file. 3 /*--- 4 es6id: 12.10.3 5 description: Invocation of `Symbol.toPrimitive` method during coercion 6 info: | 7 [...] 8 7. Return the result of performing Abstract Equality Comparison rval == 9 lval. 10 11 ES6 Section 7.2.12 Abstract Equality Comparison 12 13 [...] 14 10. If Type(x) is either String, Number, or Symbol and Type(y) is Object, 15 then return the result of the comparison x == ToPrimitive(y). 16 17 ES6 Section 7.1.1 ToPrimitive ( input [, PreferredType] ) 18 19 1. If PreferredType was not passed, let hint be "default". 20 [...] 21 4. Let exoticToPrim be GetMethod(input, @@toPrimitive). 22 5. ReturnIfAbrupt(exoticToPrim). 23 6. If exoticToPrim is not undefined, then 24 a. Let result be Call(exoticToPrim, input, «hint»). 25 [...] 26 features: [Symbol.toPrimitive] 27 ---*/ 28 29 var y = {}; 30 var callCount = 0; 31 var thisVal, args; 32 33 y[Symbol.toPrimitive] = function() { 34 callCount += 1; 35 thisVal = this; 36 args = arguments; 37 }; 38 39 0 == y; 40 41 assert.sameValue(callCount, 1, 'method invoked exactly once'); 42 assert.sameValue(thisVal, y, '`this` value is the object being compared'); 43 assert.sameValue(args.length, 1, 'method invoked with exactly one argument'); 44 assert.sameValue( 45 args[0], 46 'default', 47 'method invoked with the string "default" as the first argument' 48 ); 49 50 reportCompare(0, 0);