generic-slice

Array.prototype.slice.call()-like method for TypedArrays, Buffers and Arguments

npm install generic-slice
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generic-slice

A poly fill for slice that uniformly and efficiently implements Array-like semantics for the following classses of objects:

  • Typed Arrays
  • Node.JS-style Buffers()
  • Regular JS Arrays
  • Arguments
  • Any other array-like object (ie has a length and array accessors)

Install

npm install generic-slice

Example

var slice = require("generic-slice")

var x = new Float32Array(4)
x[0] = 1
x[1] = 2
x[2] = 3
x[3] = 4

var y = slice(x, 0, 2)

// Now:
//      y = [ 1, 2 ]
//      x = [ 1, 2, 3, 4 ]


y[0] = 1000

// Now:
//      y = [ 1000, 2 ]
//      x = [ 1, 2, 3, 4 ]

require("generic-slice")(array[, sliceBegin, sliceEnd])

A generic polyfill for slicing array-like objects.

  • array is a typed array, buffer, Array, or Arguments object
  • sliceBegin is an optional argument giving the start of the slice. Negative values change counting to end of array. (Default: 0)
  • sliceEnd is an optional argument giving the end of the slice. Negative values wrap around. (Default: array.length)

Returns A copy of the array from the range [sliceBegin, sliceEnd)

Why make this?

Because:

  • slice got dropped from the typed array specification (and the replacement method, .subarray() merely returns a view and does not make a copy)
  • Node.JS's Buffer's slice method does not make a copy like Array's slice does, and so it has inconsistent semantics.
  • Arguments doesn't have a slice method either
  • Using Array.prototype.slice.call doesn't properly preserve the types of things like Buffers or typed arrays
  • Also Array.prototype.slice.call can be slower than an appropriate implementation. For example, to clone a typed array you can slice the underlying ArrayBuffer assuming that you are careful about how you perform indexing.

Is it thoroughly tested?

All of the major edge cases should be tested. If you find a bug, please open an issue or send a pull request.

Credits

(c) 2013 Mikola Lysenko. MIT License

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