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    node-int64
    DefinitelyTyped icon, indicating that this package has TypeScript declarations provided by the separate @types/node-int64 package

    0.4.0 • Public • Published

    JavaScript Numbers are represented as IEEE 754 double-precision floats. Unfortunately, this means they lose integer precision for values beyond +/- 2^^53. For projects that need to accurately handle 64-bit ints, such as node-thrift, a performant, Number-like class is needed. Int64 is that class.

    Int64 instances look and feel much like JS-native Numbers. By way of example ...

    // First, let's illustrate the problem ...
    > (0x123456789).toString(16)
    '123456789' // <- what we expect.
    > (0x123456789abcdef0).toString(16)
    '123456789abcdf00' // <- Ugh!  JS doesn't do big ints. :(
     
    // So let's create a couple Int64s using the above values ...
     
    // Require, of course
    > Int64 = require('node-int64')
     
    // x's value is what we expect (the decimal value of 0x123456789)
    > x = new Int64(0x123456789)
    [Int64 value:4886718345 octets:00 00 00 01 23 45 67 89]
     
    // y's value is Infinity because it's outside the range of integer
    // precision.  But that's okay - it's still useful because it's internal
    // representation (octets) is what we passed in
    > y = new Int64('123456789abcdef0')
    [Int64 value:Infinity octets:12 34 56 78 9a bc de f0]
     
    // Let's do some math.  Int64's behave like Numbers.  (Sorry, Int64 isn't
    // for doing 64-bit integer arithmetic (yet) - it's just for carrying
    // around int64 values
    > x + 1
    4886718346
    > y + 1
    Infinity
     
    // Int64 string operations ...
    > 'value: ' + x
    'value: 4886718345'
    > 'value: ' + y
    'value: Infinity'
    > x.toString(2)
    '100100011010001010110011110001001'
    > y.toString(2)
    'Infinity'
     
    // Use JS's isFinite() method to see if the Int64 value is in the
    // integer-precise range of JS values
    > isFinite(x)
    true
    > isFinite(y)
    false
     
    // Get an octet string representation.  (Yay, y is what we put in!)
    > x.toOctetString()
    '0000000123456789'
    > y.toOctetString()
    '123456789abcdef0'
     
    // Finally, some other ways to create Int64s ...
     
    // Pass hi/lo words
    > new Int64(0x12345678, 0x9abcdef0)
    [Int64 value:Infinity octets:12 34 56 78 9a bc de f0]
     
    // Pass a Buffer
    > new Int64(new Buffer([0x12, 0x34, 0x56, 0x78, 0x9a, 0xbc, 0xde, 0xf0]))
    [Int64 value:Infinity octets:12 34 56 78 9a bc de f0]
     
    // Pass a Buffer and offset
    > new Int64(new Buffer([0,0,0,0,0x12, 0x34, 0x56, 0x78, 0x9a, 0xbc, 0xde, 0xf0]), 4)
    [Int64 value:Infinity octets:12 34 56 78 9a bc de f0]
     
    // Pull out into a buffer
    > new Int64(new Buffer([0x12, 0x34, 0x56, 0x78, 0x9a, 0xbc, 0xde, 0xf0])).toBuffer()
    <Buffer 12 34 56 78 9a bc de f0>
     
    // Or copy into an existing one (at an offset)
    > var buf = new Buffer(1024);
    > new Int64(new Buffer([0x12, 0x34, 0x56, 0x78, 0x9a, 0xbc, 0xde, 0xf0])).copy(buf, 512);

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    Version

    0.4.0

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