字符串数组去重 ["a","b","c","a","b","c"] --> ["a","b","c"]

非正则实现：

let str_arr=["a","b","c","a","b","c"]

function unique(arr){

  return [...new Set(arr)]

}

console.log(unique(str_arr)) // ["a","b","c"]

用正则实现：

var str_arr = ["a", "b", "c", "a", "b", "c"]

function unique(arr) {

    return arr.sort().join(",,").

    replace(/(,|^)([^,]+)(,,\2)+(,|$)/g, "$1$2$4").

    replace(/,,+/g, ",").

    replace(/,$/, "").

    split(",")

}

console.log(unique(str_arr)) // ["a","b","c"]