just/packages/array-mode/index.js at skew · hmmhmmhm/just

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module.exports = mode;

function mode(arr) {

if (!Array.isArray(arr)) {

arr = [].slice.call(arguments);

}

var map = {};

var ArrLen = arr.length;

for (var i = 0; i < ArrLen; i++) {

var n = arr[i];

if (!Number.isFinite(n)) {

throw new Error('all values passed to `mode` must be numeric');

}

n in map ? map[n]++ : (map[n] = 1);

}

var mapKeys = Object.keys(map);

var mapKeysLen = mapKeys.length;

if (!mapKeysLen) {

throw new Error('no values were passed to `mode`');

}

var maxOccurences = -1;

var result;

for (var i = 0; i < mapKeysLen; i++) {

var thisKey = mapKeys[i];

if (map[thisKey] > maxOccurences) {

result = [Number(thisKey)];

maxOccurences = map[thisKey];

} else if (map[thisKey] == maxOccurences) {

result.push(Number(thisKey));

}

return result.length > 1

? result.sort(function(a, b) {

return a >= b ? 1 : -1;

})

: result[0];

}