toPrimitive.js - mozsearch

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// ES6 19.4.3.4 Symbol.prototype[@@toPrimitive](hint)

// This method gets the primitive symbol from a Symbol wrapper object.

var sym = Symbol.for("truth")

var obj = Object(sym);

assertEq(obj[Symbol.toPrimitive]("default"), sym);

// The hint argument is ignored.

assertEq(obj[Symbol.toPrimitive]("number"), sym);

assertEq(obj[Symbol.toPrimitive]("string"), sym);

assertEq(obj[Symbol.toPrimitive](), sym);

assertEq(obj[Symbol.toPrimitive](Math.atan2), sym);

// The this value can also be a primitive symbol.

assertEq(sym[Symbol.toPrimitive](), sym);

// Or a wrapper to a Symbol object in another compartment.

var obj2 = newGlobal().Object(sym);

assertEq(obj2[Symbol.toPrimitive]("default"), sym);

// Otherwise a TypeError is thrown.

var symbolToPrimitive = Symbol.prototype[Symbol.toPrimitive];

var nonSymbols = [

    undefined, null, true, 13, NaN, "justice", {}, [sym],

    symbolToPrimitive,

    new Proxy(obj, {})

];

for (var value of nonSymbols) {

    assertThrowsInstanceOf(() => symbolToPrimitive.call(value, "string"), TypeError);

// Surface features:

assertEq(symbolToPrimitive.name, "[Symbol.toPrimitive]");

var desc = Object.getOwnPropertyDescriptor(Symbol.prototype, Symbol.toPrimitive);

assertEq(desc.configurable, true);

assertEq(desc.enumerable, false);

assertEq(desc.writable, false);

reportCompare(0, 0);