packed-arrays.js - mozsearch

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var isPacked = getSelfHostedValue("IsPackedArray");

function test() {

    var arr;

    // basic

    arr = [];

    assertEq(isPacked(arr), true);

    arr[0] = 0;

    assertEq(isPacked(arr), true);

    arr[2] = 2;

    assertEq(isPacked(arr), false);

    // delete

    arr = [1, 2, 3];

    assertEq(isPacked(arr), true);

    delete arr[1];

    assertEq(isPacked(arr), false);

    // setting .length

    arr = [1];

    arr.length = 0;

    assertEq(isPacked(arr), true);

    arr.length = 1;

    assertEq(isPacked(arr), false);

    // slice

    arr = [1, 2, , 3];

    assertEq(isPacked(arr), false);

    assertEq(isPacked(arr.slice(0, 2)), true);

    assertEq(isPacked(arr.slice(0, 3)), false);

    assertEq(isPacked(arr.slice(2, 3)), false);

    assertEq(isPacked(arr.slice(3, 4)), true);

    // splice

    arr = [1, 2, 3];

    assertEq(isPacked(arr.splice(0)), true);

    arr = [1, , 2];

    assertEq(isPacked(arr.splice(0)), false);

    arr = [1, , 2];

    assertEq(isPacked(arr.splice(0, 1)), true);

    assertEq(arr.length, 2);

    assertEq(isPacked(arr.splice(0, 1)), false);

    assertEq(arr.length, 1);

    assertEq(isPacked(arr.splice(0, 1)), true);

    assertEq(arr.length, 0);

    assertEq(isPacked(arr.splice(0)), true);

for (var i = 0; i < 5; i++) {

    test();