Source code
Revision control
Copy as Markdown
Other Tools
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
// Trailing comma in Arguments production.
// 12.3 Left-Hand-Side Expressions
// Arguments[Yield]:
// ()
// ( ArgumentList[?Yield] )
// ( ArgumentList[?Yield] , )
function argsLength() {
return {value: arguments.length};
}
function sum(...rest) {
return {value: rest.reduce((a, c) => a + c, 0)};
}
function call(f, argList) {
return eval(`(${f}(${argList})).value`);
}
function newCall(F, argList) {
return eval(`(new ${F}(${argList})).value`);
}
function superCall(superClass, argList) {
return eval(`(new class extends ${superClass} {
constructor() {
super(${argList});
}
}).value`);
}
// Ensure the correct number of arguments is passed.
for (let type of [call, newCall, superCall]) {
let test = type.bind(null, "argsLength");
assertEq(test("10, "), 1);
assertEq(test("10, 20, "), 2);
assertEq(test("10, 20, 30, "), 3);
assertEq(test("10, 20, 30, 40, "), 4);
assertEq(test("...[10, 20], "), 2);
assertEq(test("...[10, 20], 30, "), 3);
assertEq(test("...[10, 20], ...[30], "), 3);
}
// Ensure the arguments themselves are passed correctly.
for (let type of [call, newCall, superCall]) {
let test = type.bind(null, "sum");
assertEq(test("10, "), 10);
assertEq(test("10, 20, "), 30);
assertEq(test("10, 20, 30, "), 60);
assertEq(test("10, 20, 30, 40, "), 100);
assertEq(test("...[10, 20], "), 30);
assertEq(test("...[10, 20], 30, "), 60);
assertEq(test("...[10, 20], ...[30], "), 60);
}
// Error cases.
for (let type of [call, newCall, superCall]) {
let test = type.bind(null, "f");
// Trailing comma in empty arguments list.
assertThrowsInstanceOf(() => test(","), SyntaxError);
// Leading comma.
assertThrowsInstanceOf(() => test(", a"), SyntaxError);
assertThrowsInstanceOf(() => test(", ...a"), SyntaxError);
// Multiple trailing comma.
assertThrowsInstanceOf(() => test("a, , "), SyntaxError);
assertThrowsInstanceOf(() => test("...a, , "), SyntaxError);
// Elision.
assertThrowsInstanceOf(() => test("a, , b"), SyntaxError);
}
if (typeof reportCompare === "function")
reportCompare(0, 0);