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function test() {
var from, to;
// From values.
from = {x: 1, y: 2};
({...to} = from);
assertEq(to.y, 2);
var z;
from = {x: 1, y: 2};
({x: z, ...to} = from);
assertEq(z, 1);
assertEq(to.y, 2);
// From getter.
var c = 7;
from = {x: 1, get y() { return ++c; }};
({...to} = from);
assertEq(c, 8);
assertEq(to.y, 8);
from = {x: 1, get y() { return ++c; }};
({y: z, ...to} = from);
assertEq(c, 9);
assertEq(z, 9);
assertEq(to.y, undefined);
// Array with dense elements.
from = [1, 2, 3];
({...to} = from);
assertEq(to[2], 3);
assertEq("length" in to, false);
from = [1, 2, 3];
({2: z, ...to} = from);
assertEq(z, 3);
assertEq(to[2], undefined);
assertEq(to[0], 1);
assertEq("length" in to, false);
// Object with sparse elements and symbols.
from = {x: 1, 1234567: 2, 1234560: 3, [Symbol.iterator]: 5, z: 3};
({...to} = from);
assertEq(to[1234567], 2);
assertEq(Object.keys(to).toString(), "1234560,1234567,x,z");
assertEq(to[Symbol.iterator], 5);
from = {x: 1, 1234567: 2, 1234560: 3, [Symbol.iterator]: 5, z: 3};
({[Symbol.iterator]: z, ...to} = from);
assertEq(to[1234567], 2);
assertEq(Object.keys(to).toString(), "1234560,1234567,x,z");
assertEq(to[Symbol.iterator], undefined);
assertEq(z, 5);
// Typed array.
from = new Int32Array([1, 2, 3]);
({...to} = from);
assertEq(to[1], 2);
from = new Int32Array([1, 2, 3]);
({1: z, ...to} = from);
assertEq(z, 2);
assertEq(to[1], undefined);
assertEq(to[2], 3);
// Primitive string.
from = "foo";
({...to} = from);
assertEq(to[0], "f");
from = "foo";
({0: z, ...to} = from);
assertEq(z, "f");
assertEq(to[0], undefined);
assertEq(to[1], "o");
// String object.
from = new String("bar");
({...to} = from);
assertEq(to[2], "r");
from = new String("bar");
({1: z, ...to} = from);
assertEq(z, "a");
assertEq(to[1], undefined);
assertEq(to[2], "r");
}
test();
test();
test();
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