不斷地取出與上一次不重複的元素

no-coflict-series.js

/**
 *       EXAMPLE:
 *          const factory = require('no-coflict-series');
 *
 *          const series = factory([1, 4, 3, 2, 7]);
 *          
 *          console.log( series.next() );
 *          console.log( series.next() );
 *          console.log( series.next() );
 *          console.log( series.next() );
 *          console.log( series.next() );
 *
 *          console.log( series.dump() );      
 * 
 */


const {shuffle} = require('lodash');

module.exports = arr => {
    const len = arr.length;
    let idx = 0;
    
    arr = shuffle(arr);

    const next = () => {
        let ret = arr[idx];

        if(idx === len - 2) {
            const arrClone = [...arr];
            const last = arrClone.pop();
            arr = [last, ...shuffle(arrClone)];
            idx = 0;
        } else {
            idx += 1;
        }

        return ret;
    }

    return {
        next,
        dump() { return arr },
    }
};