array-length.js

Google浏览器V8内核代码

// Copyright 2008 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
//       notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
//       copyright notice, this list of conditions and the following
//       disclaimer in the documentation and/or other materials provided
//       with the distribution.
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//       contributors may be used to endorse or promote products derived
//       from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

var a = [0,1,2,3];
a.length = 0;

assertEquals('undefined', typeof a[0]);
assertEquals('undefined', typeof a[1]);
assertEquals('undefined', typeof a[2]);
assertEquals('undefined', typeof a[3]);


var a = [0,1,2,3];
a.length = 2;

assertEquals(0, a[0]);
assertEquals(1, a[1]);
assertEquals('undefined', typeof a[2]);
assertEquals('undefined', typeof a[3]);


var a = new Array();
a[0] = 0;
a[1000] = 1000;
a[1000000] = 1000000;
a[2000000] = 2000000;

assertEquals(2000001, a.length);
a.length = 0;
assertEquals(0, a.length);
assertEquals('undefined', typeof a[0]);
assertEquals('undefined', typeof a[1000]);
assertEquals('undefined', typeof a[1000000]);
assertEquals('undefined', typeof a[2000000]);


var a = new Array();
a[0] = 0;
a[1000] = 1000;
a[1000000] = 1000000;
a[2000000] = 2000000;

assertEquals(2000001, a.length);
a.length = 2000;
assertEquals(2000, a.length);
assertEquals(0, a[0]);
assertEquals(1000, a[1000]);
assertEquals('undefined', typeof a[1000000]);
assertEquals('undefined', typeof a[2000000]);


var a = new Array();
a[Math.pow(2,31)-1] = 0;
a[Math.pow(2,30)-1] = 0;
assertEquals(Math.pow(2,31), a.length);


var a = new Array();
a[0] = 0;
a[1000] = 1000;
a[Math.pow(2,30)-1] = Math.pow(2,30)-1;
a[Math.pow(2,31)-1] = Math.pow(2,31)-1;
a[Math.pow(2,32)-2] = Math.pow(2,32)-2;

assertEquals(Math.pow(2,30)-1, a[Math.pow(2,30)-1]);
assertEquals(Math.pow(2,31)-1, a[Math.pow(2,31)-1]);
assertEquals(Math.pow(2,32)-2, a[Math.pow(2,32)-2]);

assertEquals(Math.pow(2,32)-1, a.length);
a.length = Math.pow(2,30)+1;  // not a smi!
assertEquals(Math.pow(2,30)+1, a.length);

assertEquals(0, a[0]);
assertEquals(1000, a[1000]);
assertEquals(Math.pow(2,30)-1, a[Math.pow(2,30)-1]);
assertEquals('undefined', typeof a[Math.pow(2,31)-1]);
assertEquals('undefined', typeof a[Math.pow(2,32)-2], "top");


var a = new Array();
a.length = new Number(12);
assertEquals(12, a.length);


var o = { length: -23 };
Array.prototype.pop.apply(o);
assertEquals(4294967272, o.length);