tor-browser

The Tor Browser
git clone https://git.dasho.dev/tor-browser.git
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bug653153.js (2573B)

      1 // ES5 15.1.2.2 step 1
      2 
      3 /*
      4 * Boundary testing for super-large positive numbers between non-exponential
      5 * and in-exponential-form.
      6 *
      7 * NB: While 1e21 is exactly representable as an IEEE754 double-precision
      8 * number, its nearest neighboring representable values are a good distance
      9 * away, 65536 to be precise.
     10 */
     11 
     12 // This is the boundary in theory.
     13 assertEq(parseInt(1e21), 1);
     14 
     15 // This is the boundary in practice.
     16 assertEq(parseInt(1e21 - 65537) > 1e20, true);
     17 assertEq(parseInt(1e21 - 65536), 1);
     18 assertEq(parseInt(1e21 + 65536), 1);
     19 
     20 // Check that we understand floating point accuracy near the boundary
     21 assertEq(1e21 - 65537 !== 1e21 - 65536, true);
     22 assertEq(1e21 - 65536, 1e21);
     23 assertEq(1e21 + 65535, 1e21);
     24 assertEq(1e21 + 65536, 1e21);
     25 
     26 // ES5 leaves exact precision in ToString(bigMagNum) undefined, which
     27 // might make this value inconsistent across implementations (maybe,
     28 // nobody's done the math here).  Regardless, it's definitely a number
     29 // very close to 1, and not a large-magnitude positive number.
     30 assertEq(1e21 + 65537 !== 1e21, true);
     31 assertEq(parseInt(1e21 + 65537) < 1.001, true);
     32 
     33 
     34 /*
     35 * Now do the same tests for super-large negative numbers crossing the
     36 * opposite boundary.
     37 */
     38 
     39 // This is the boundary in theory.
     40 assertEq(parseInt(-1e21), -1);
     41 
     42 // This is the boundary in practice.
     43 assertEq(parseInt(-1e21 + 65537) < -1e20, true);
     44 assertEq(parseInt(-1e21 + 65536), -1);
     45 assertEq(parseInt(-1e21 - 65536), -1);
     46 
     47 // Check that we understand floating point accuracy near the boundary
     48 assertEq(-1e21 + 65537 !== -1e21 + 65536, true);
     49 assertEq(-1e21 + 65536, -1e21);
     50 assertEq(-1e21 - 65535, -1e21);
     51 assertEq(-1e21 - 65536, -1e21);
     52 
     53 // ES5 leaves exact precision in ToString(bigMagNum) undefined, which
     54 // might make this value inconsistent across implementations (maybe,
     55 // nobody's done the math here).  Regardless, it's definitely a number
     56 // very close to -1, and not a large-magnitude negative number.
     57 assertEq(-1e21 - 65537 !== 1e21, true);
     58 assertEq(parseInt(-1e21 - 65537) > -1.001, true);
     59 
     60 
     61 /* Check values around the boundary. */
     62 arr = [1e0, 5e1, 9e19, 0.1e20, 1.3e20, 1e20, 9e20, 9.99e20, 0.1e21,
     63       1e21, 1.0e21, 2e21, 2e20, 2.1e22, 9e21, 0.1e22, 1e22, 3e46, 3e23, 3e100, 3.4e200, 7e1000,
     64       1e21, 1e21+65537, 1e21+65536, 1e21-65536, 1e21-65537]; 
     65 
     66 /* Check across a range of values in case we missed anything. */
     67 for (var i = 0; i < 4000; i++) {
     68    arr.push(1e19 + i*1e19);
     69 }
     70 
     71 for (var i in arr) {
     72    assertEq(parseInt( arr[i]), parseInt(String( arr[i])));
     73    assertEq(parseInt(-arr[i]), parseInt(String(-arr[i])));
     74 }