使用if语句的条件循环(Conditional loop using if statement)

 我正在学习一些基本的javascript，并希望学习如何在满足某些条件时返回到方法的开头。 
 
 在这种情况下，用户必须在提示中输入一个字符才能继续执行“您输入的字符是”字符串的语句。 我想实现一个循环，如果没有输入任何内容，则将程序发送回方法的开头。 到目前为止，我有以下内容： 
 
<script class="promptwindow">            
        var x
        x = prompt("Please type a character in the box and click OK", "")

        if (x = null)
            {****}

        document.write("The character you typed was ", x)    
</script>
 
 我不确定在****括号中使用什么，我需要类似于goto东西。 
 
 编辑：是的，应该是== 。 我会把错误留在那里，以便评论有意义。 

I'm learning some basic javascript, and would like to learn how to return to the beginning of a method when certain conditions are met.
 
In this scenario, the user must enter a character in the prompt in order to proceed to the statment "The character you typed was" string. I would like to implement a loop to send the program back to the start of the method if nothing is entered. I have the following, so far:
 
<script class="promptwindow">            
        var x
        x = prompt("Please type a character in the box and click OK", "")

        if (x = null)
            {****}

        document.write("The character you typed was ", x)    
</script>
 
I'm unsure what to use in the **** bracket, I need something similar to goto.
 
Edit: Yep, should have been ==. I'll leave the mistake there so that the comments make sense.

原文：https://stackoverflow.com/questions/25526879