1. javascript的replace函数  
  2. "aaa".replace("a","A")   ---> "Aaa"  
  3. // 正则表达式替换实现replaceAll效果  
  4. "aaa".replace(/a/g,"A")   ---> "AAA"  
  5.   
  6. $("#machine_nos").val($("#machine_nos").val().replace(/:/g,":").replace(/,/g,","));