npm i math-permutation --save
var permutation = require('math-permutation')
var arr = [1, 2, 3]
//Get all conditions that conbine two element of the the arr(different order different condition)
combination.cmn(arr, 2)
//Get all conditions that conbine two element of the the arr(different order different condition and element can repeat)
combination.cmnWithRepetition(arr, 2)
Only support for array of String or Number