array-from-copies.js

// Array.from copies an array.

load(libdir + "asserts.js");

var testArray = [1, 2, 3];

//test that Array.from creates a new array
assertDeepEq(Array.from(testArray), testArray);
assertEq(Array.from(testArray) === testArray, false);
assertEq(Array.from(testArray) === Array.from(testArray), false);

array-from-iterable.js

// If an object has both .length and [@@iterator] properties, [@@iterator] is used.

load(libdir + "iteration.js");
load(libdir + "asserts.js");

var a = ['a', 'e', 'i', 'o', 'u'];
a[std_iterator] = function* () {
    for (var i = this.length; i--; )
        yield this[i];
};

var log = '';
function f(x) {
    log += x;
    return x + x;
}

var b = Array.from(a, f);
assertDeepEq(b, ['uu', 'oo', 'ii', 'ee', 'aa']);
assertEq(log, 'uoiea');

array-from-string.js

// Array.from string

load(libdir + "asserts.js");

var testString = "test string";
assertDeepEq(Array.from(testString), ['t', 'e', 's', 't', ' ', 's', 't', 'r', 'i', 'n', 'g']);

array-from-surrogate-pair.js

// Array.from string iterator maintains surrogate pairs.

load(libdir + "asserts.js");

var pairString = "\uD834\uDF06";
assertDeepEq(Array.from(pairString), [pairString]);

array-from-typeerror.js

// Array.from: Assert typeerror if arrayLike is undefined or null

load(libdir + "asserts.js");

assertThrowsInstanceOf(() => Array.from(undefined), TypeError);
assertThrowsInstanceOf(() => Array.from(null), TypeError);