js 去掉以逗號分割的字符串中頭尾和中間多余的逗號

let permission = ",,,106,105,108,,,109,110,107,,101,,,"

let permission = "106,105,108,109,110,107,101"

我們要把上面的字符串處理成想要的結果，最好的方法是使用正則，我的正則一直寫不太好，就想換個思路解決。

首先想到個最笨的辦法，先掐頭去尾再解決中間的，但這也不是理解的辦法，要寫一大行代碼，還容易 出錯

就想到先把它轉換成數組，再對數組去空，然后再轉回字符串，完美解決

let permission = ",,,106,105,108,,,109,110,107,,101,,,"
    console.log("permission",permission)
    arry = permission.split(",");
    console.log("arry",arry)
    let arry2 =[]
    arry.map((item)=>{
        if (item !== "" && item != undefined) {
            arry2.push(item);
        }
    })
    arry2 = arry2.join(',')
    console.log("arry2",arry2)