JS 字符串指定位置插入值

function insertStr(soure, firstPosition, firstStr, secondPosition, secondStr) {
    
    
    soure = soure.slice(0, firstPosition) + firstStr + soure.slice(firstPosition)
    return soure.slice(0, secondPosition) + secondStr + soure.slice(secondPosition)
}

let currentTime = 20210107

consolog(insertStr(currentTime, 4, '-', 7, '-'))

// 输出

2021-01-07