src/third_party/mozjs-45/js/src/tests/ecma_6/TypedArray/from_mapping.js

const constructors = [
    Int8Array,
    Uint8Array,
    Uint8ClampedArray,
    Int16Array,
    Uint16Array,
    Int32Array,
    Uint32Array,
    Float32Array,
    Float64Array ];

if (typeof SharedArrayBuffer != "undefined")
    constructors.push(sharedConstructor(Int8Array),
		      sharedConstructor(Uint8Array),
		      sharedConstructor(Int16Array),
		      sharedConstructor(Uint16Array),
		      sharedConstructor(Int32Array),
		      sharedConstructor(Uint32Array),
		      sharedConstructor(Float32Array),
		      sharedConstructor(Float64Array));

for (var constructor of constructors) {
    // If the mapfn argument to %TypedArray%.from is undefined, don't map.
    assertDeepEq(constructor.from([3, 4, 5], undefined), new constructor([3, 4, 5]));
    assertDeepEq(constructor.from([4, 5, 6], undefined, Math), new constructor([4, 5, 6]));

    // mapfn is called with two arguments: value and index.
    var log = [];
    function f(...args) {
        log.push(args);
        return log.length;
    }
    assertDeepEq(constructor.from(['a', 'e', 'i', 'o', 'u'], f), new constructor([1, 2, 3, 4, 5]));
    assertDeepEq(log, [['a', 0], ['e', 1], ['i', 2], ['o', 3], ['u', 4]]);

    // If the object to be copied is non-iterable, mapfn is still called with two
    // arguments.
    log = [];
    assertDeepEq(constructor.from({0: "zero", 1: "one", length: 2}, f), new constructor([1, 2]));
    assertDeepEq(log, [["zero", 0], ["one", 1]]);

    // If the object to be copied is iterable and the constructor is not Array,
    // mapfn is still called with two arguments.
    log = [];
    function C() {}
    C.from = constructor.from;
    var c = new C;
    c[0] = 1;
    c[1] = 2;
    assertDeepEq(C.from(["zero", "one"], f), c);
    assertDeepEq(log, [["zero", 0], ["one", 1]]);

    // The mapfn is called even if the value to be mapped is undefined.
    assertDeepEq(constructor.from([0, 1, , 3], String), new constructor(["0", "1", "undefined", "3"]));
    var arraylike = {length: 4, "0": 0, "1": 1, "3": 3};
    assertDeepEq(constructor.from(arraylike, String), new constructor(["0", "1", "undefined", "3"]));
}

// %TypedArray%.from(obj, map) is not exactly the same as %TypedArray%.from(obj).map(mapFn).
assertDeepEq(Int8Array.from([150], v => v / 2), new Int8Array([75]));
// Uncomment the following line when we implement the .map method.
// assertDeepEq(Int8Array.from([150]).map(v => v / 2), new Int8Array([-53]));

if (typeof reportCompare === "function")
    reportCompare(true, true);