javascript - 如果q等于零，则s等于零。

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                7年前关闭。
            
        

回答了这个问题。但是stackoverflow不会让我问其他问题。有人可以帮忙吗？

最佳答案

声明s并将其默认设置为空字符串。如果q1不为空，则为分配一个值。否则s仍然是一个空字符串。在代码的更高版本中，您可以将文本框设置为填充s，如果q1为空，则s也将填充为s，因此此处将不显示任何内容。

//declare s and set it to default to an empty string
var s = ''
//make sure q1 is defined and not null
if (q1 != undefined && q1 != null)
   //if q1 is not empty, then set it equal to '_'+n1+'. '+q1,
   //otherwise s will be an empty string
   if (q1 != '')
       s = '_'+n1+'. '+q1
//if s is empty you can do something,
//OR you can just set your input value to equal s
if (s == '')
    //do some stuff here