destructuring-assignment-accepts-iterables.js [plain text]
function shouldBe(actual, expected) {
if (actual !== expected)
throw new Error('bad value: ' + actual);
}
function shouldThrow(func, errorMessage) {
var errorThrown = false;
var error = null;
try {
func();
} catch (e) {
errorThrown = true;
error = e;
}
if (!errorThrown)
throw new Error('not thrown');
if (String(error) !== errorMessage)
throw new Error(`bad error: ${String(error)}`);
}
(function () {
var [a, b, c] = [1, 2, 3];
shouldBe(a, 1);
shouldBe(b, 2);
shouldBe(c, 3);
}());
(function () {
var [a, b, c] = [1, 2, 3].keys();
shouldBe(a, 0);
shouldBe(b, 1);
shouldBe(c, 2);
}());
(function () {
var [a, b, c] = [1, 2, 3].values();
shouldBe(a, 1);
shouldBe(b, 2);
shouldBe(c, 3);
}());
(function () {
var [a, , c] = [1, 2, 3].values();
shouldBe(a, 1);
shouldBe(c, 3);
}());
(function () {
var [a, b, c] = [1, , 3].values();
shouldBe(a, 1);
shouldBe(b, undefined);
shouldBe(c, 3);
}());
(function () {
var [, b, c] = [1, 2, 3, 4, 5, 6].values();
shouldBe(b, 2);
shouldBe(c, 3);
}());
(function () {
var [a, b, c] = [1].values();
shouldBe(a, 1);
shouldBe(b, undefined);
shouldBe(c, undefined);
}());
(function ([a, b, c]) {
shouldBe(a, 1);
shouldBe(b, undefined);
shouldBe(c, undefined);
}([1].values()));
(function () {
var [a = 0, b = 2, c = 3] = [1].values();
shouldBe(a, 1);
shouldBe(b, 2);
shouldBe(c, 3);
}());
(function () {
var [a = 1, b = 2, c = 3] = [undefined, undefined, undefined];
shouldBe(a, 1);
shouldBe(b, 2);
shouldBe(c, 3);
}());
(function () {
var string = "𠮷野家";
var [a, b, c] = string;
shouldBe(string.length, 4);
shouldBe(a, '𠮷');
shouldBe(b, '野');
shouldBe(c, '家');
}());
(function () {
var set = new Set([1, 2, 3]);
var [a, b, c] = set;
shouldBe(set.has(a), true);
shouldBe(set.has(b), true);
shouldBe(set.has(c), true);
}());
(function () {
var map = new Map([[1, 1], [2, 2], [3, 3]]);
var [a, b, c] = map;
shouldBe(Array.isArray(a), true);
shouldBe(Array.isArray(b), true);
shouldBe(Array.isArray(c), true);
shouldBe(map.has(a[0]), true);
shouldBe(map.has(b[0]), true);
shouldBe(map.has(c[0]), true);
}());
shouldThrow(function () {
var [a, b, c] = {
[Symbol.iterator]() {
return 42;
}
};
}, "TypeError: [a, b, c] is not a function. (In '[a, b, c]', '[a, b, c]' is undefined)");
shouldThrow(function () {
var [a, b, c] = {
[Symbol.iterator]() {
return {};
}
};
}, "TypeError: [a, b, c] is not a function. (In '[a, b, c]', '[a, b, c]' is undefined)");
shouldThrow(function () {
var [a, b, c] = {
[Symbol.iterator]() {
return this;
},
next() {
throw new Error('out');
}
};
}, 'Error: out');
shouldThrow(function () {
var [a, b, c] = {
[Symbol.iterator]() {
return this;
},
next() {
return 42;
}
};
}, 'TypeError: Iterator result interface is not an object.');
(function () {
var ok = 0;
shouldThrow(function () {
var [a, b, c] = {
[Symbol.iterator]() {
return this;
},
return() {
ok++;
},
next() {
return 42;
}
};
}, 'TypeError: Iterator result interface is not an object.');
shouldBe(ok, 0);
}());
(function () {
var ok = 0;
shouldThrow(function () {
var [a, b, c] = {
[Symbol.iterator]() {
return this;
},
return() {
ok++;
},
next() {
return { value: 20, done: false };
}
};
}, 'TypeError: Iterator result interface is not an object.');
shouldBe(ok, 1);
}());
(function () {
var ok = 0;
var [a, b, c] = {
[Symbol.iterator]() {
return this;
},
return() {
ok++;
},
next() {
return { value: 20, done: true };
}
};
shouldBe(a, undefined);
shouldBe(b, undefined);
shouldBe(c, undefined);
shouldBe(ok, 0);
}());
(function () {
var ok = 0;
var n = 0;
var done = false;
var [a, b, c] = {
[Symbol.iterator]() {
return this;
},
return() {
ok++;
},
next() {
var prev = done;
done = true;
++n;
return { value: 20, done: prev };
}
};
shouldBe(a, 20);
shouldBe(b, undefined);
shouldBe(c, undefined);
shouldBe(n, 2);
shouldBe(ok, 0);
}());
(function () {
var ok = 0;
var n = 0;
var done = false;
var [a, b, c] = {
[Symbol.iterator]() {
return this;
},
return() {
++ok;
return { done: true };
},
next() {
++n;
return { value: 20, done: false };
}
};
shouldBe(a, 20);
shouldBe(b, 20);
shouldBe(c, 20);
shouldBe(n, 3);
shouldBe(ok, 1);
}());
(function () {
var ok = 0;
var n = 0;
var done = false;
var [a, b, c] = {
[Symbol.iterator]() {
return this;
},
return() {
++ok;
return { done: true };
},
count: 0,
next() {
++n;
var done = ++this.count === 3;
return { value: 20, done };
}
};
shouldBe(a, 20);
shouldBe(b, 20);
shouldBe(c, undefined);
shouldBe(n, 3);
shouldBe(ok, 0);
}());
(function () {
var ok = 0;
var n = 0;
var done = false;
var [a, b, c] = {
[Symbol.iterator]() {
return this;
},
return() {
++ok;
return { done: true };
},
count: 0,
next() {
++n;
var done = ++this.count === 4;
return { value: 20, done };
}
};
shouldBe(a, 20);
shouldBe(b, 20);
shouldBe(c, 20);
shouldBe(n, 3);
shouldBe(ok, 1);
}());
(function () {
var ok = 0;
var n = 0;
shouldThrow(function () {
var [a, b, c] = {
[Symbol.iterator]() {
return this;
},
return() {
ok++;
throw new Error('out');
},
next() {
n++;
return { value: 20, done: false };
}
};
}, 'Error: out');
shouldBe(n, 3);
shouldBe(ok, 1);
}());
(function () {
var ok = 0;
var n = 0;
shouldThrow(function () {
var [a, b, c] = {
[Symbol.iterator]() {
return this;
},
get return() {
ok++;
throw new Error('out');
},
next() {
n++;
return { value: 20, done: false };
}
};
}, 'Error: out');
shouldBe(n, 3);
shouldBe(ok, 1);
}());
(function () {
var ok = 0;
var n = 0;
shouldThrow(function () {
var [a, b, c] = {
[Symbol.iterator]() {
return this;
},
get return() {
ok++;
throw new Error('ng');
},
next() {
n++;
throw new Error('out');
}
};
}, 'Error: out');
shouldBe(n, 1);
shouldBe(ok, 0);
}());
(function () {
var ok = 0;
var n = 0;
shouldThrow(function () {
var [a, b, c] = {
[Symbol.iterator]() {
return this;
},
get return() {
ok++;
throw new Error('ng');
},
get next() {
++n;
throw new Error('out');
}
};
}, 'Error: out');
shouldBe(n, 1);
shouldBe(ok, 0);
}());