source: trip-planner-front/node_modules/array-uniq/index.js@ eed0bf8

'use strict';

// there's 3 implementations written in increasing order of efficiency

// 1 - no Set type is defined
function uniqNoSet(arr) {
        var ret = [];

        for (var i = 0; i < arr.length; i++) {
                if (ret.indexOf(arr[i]) === -1) {
                        ret.push(arr[i]);
                }
        }

        return ret;
}

// 2 - a simple Set type is defined
function uniqSet(arr) {
        var seen = new Set();
        return arr.filter(function (el) {
                if (!seen.has(el)) {
                        seen.add(el);
                        return true;
                }

                return false;
        });
}

// 3 - a standard Set type is defined and it has a forEach method
function uniqSetWithForEach(arr) {
        var ret = [];

        (new Set(arr)).forEach(function (el) {
                ret.push(el);
        });

        return ret;
}

// V8 currently has a broken implementation
// https://github.com/joyent/node/issues/8449
function doesForEachActuallyWork() {
        var ret = false;

        (new Set([true])).forEach(function (el) {
                ret = el;
        });

        return ret === true;
}

if ('Set' in global) {
        if (typeof Set.prototype.forEach === 'function' && doesForEachActuallyWork()) {
                module.exports = uniqSetWithForEach;
        } else {
                module.exports = uniqSet;
        }
} else {
        module.exports = uniqNoSet;
}