26 lines
553 B
JavaScript
26 lines
553 B
JavaScript
/**
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* Reduce an array to unique values, optionally into a separate array.
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*
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* @module reduce-unique
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* @example
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* > const unique = require('reduce-unique')
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*
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* > const arr = [ 1, 3, 8, 3, 1, 2, 1, 9, 3, 3 ]
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*
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* > arr.reduce(unique)
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* [ 1, 3, 8, 2, 9 ]
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*
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* > arr.reduce(unique, [ 'one', 'two' ])
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* [ 'one', 'two', 1, 3, 8, 2, 9 ]
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*
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* > arr.reduce([ 3 ])
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* 3
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*/
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module.exports = reduceUnique
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function reduceUnique (prev, curr) {
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if (!Array.isArray(prev)) prev = [ prev ]
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if (prev.indexOf(curr) === -1) prev.push(curr)
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return prev
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}
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