1.字符串时

     //获取逗号前后内容
     let str = "aaa,bbb"
     console.log( "逗号前",str.split(",")[0] )
     console.log( "逗号后",str.split(",")[1] )

2.数组形式时转数组对象时

 let arr = ["小明,1","小陈,5","小李,6"]
 let newarr =  arr.map( item =>{
        console.log( "逗号前",item.split(",")[0] ) 
        console.log( "逗号后",item.split(",")[1] )
        let obj = {
           name: item.split(",")[0],
           num: item.split(",")[1]
        }
        return obj
    })
  console.log("数组对象",newarr)

3. 如何获取最后一个逗后的内容

     //方法一
     let str = 'aa,bb,cc,dd'
     var index = str.lastIndexOf(",");
     str = str.substring(index + 1, str.length);
     console.log("最后一个逗后内容",str)

     //方法二
     let str = 'aa,bb,cc,dd'
     let strArr = str.split(',')
     console.log( "最后一个逗后内容",strArr[strArr.length-1] )

4. 如何获取第一个逗后前的内容

     let str = "AAA,BBB,CCC,DDD";
     let strArr = str.split(",");
     console.log( strArr[0] )

 除了逗号其符号也是同理~~

//仅供参考,如有雷同,纯属虚构