12 lines
376 B
JavaScript
12 lines
376 B
JavaScript
var _has = require('./_has.js');
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var _group = require('./_group.js');
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// Counts instances of an object that group by a certain criterion. Pass
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// either a string attribute to count by, or a function that returns the
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// criterion.
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var countBy = _group(function(result, value, key) {
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if (_has(result, key)) result[key]++; else result[key] = 1;
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});
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module.exports = countBy;
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