join-sparse.js - mozsearch

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const join = Array.prototype.join;

let obj = { length: 10 };

assertEq(join.call(obj, ""), "");

assertEq(join.call(obj), ",".repeat(9));

assertEq(join.call(obj, "abc"), "abc".repeat(9));

obj = { [0]: 1, length: 10 };

assertEq(join.call(obj, ""), "1");

assertEq(join.call(obj), "1" + ",".repeat(9));

assertEq(join.call(obj, "abc"), "1" + "abc".repeat(9));

obj = { [0]: 1, [1]: 2, [2]: 3, [3]: 4, [4]: 5, length: 2 };

assertEq(join.call(obj), "1,2");

assertEq(join.call(obj, ""), "12");

assertEq(join.call(obj, "abc"), "1abc2");

obj = { [0]: 1, [1]: 2, [2]: {}, [3]: 4, length: 3};

assertEq(join.call(obj), "1,2,[object Object]");

assertEq(join.call(obj, ""), "12[object Object]");

assertEq(join.call(obj, "abc"), "1abc2abc[object Object]");

assertEq(new Array(10).join(""), "");

assertEq(new Array(10).join(), ",".repeat(9));

assertEq(new Array(10).join("abc"), "abc".repeat(9));

assertEq(new Array(100).join(), ",".repeat(99));

assertEq(new Array(100).join(""), "");

assertEq(new Array(100).join("abc"), "abc".repeat(99));

var a = [1];

a.length = 10;

assertEq(a.join(), "1" + ",".repeat(9));

assertEq(a.join(""), "1");

assertEq(a.join("abc"), "1" + "abc".repeat(9));

var a = [1, 2, 3, 4, 5]

a.length = 2;

assertEq(a.join(), "1,2");

assertEq(a.join(""), "12");

assertEq(a.join("abc"), "1abc2");

var a = [1, 2, {}, 4];

a.length = 3;

assertEq(a.join(), "1,2,[object Object]");

assertEq(a.join(""), "12[object Object]");

assertEq(a.join("abc"), "1abc2abc[object Object]");

// Too slow:

// var obj = { [0]: 1, length: 2 ** 33 };

// join.call(obj, "");