在条件表达式中声明变量（三元运算符）(declaring a variable within conditional expressions (ternary operator))

在条件表达式中声明变量（三元运算符）(declaring a variable within conditional expressions (ternary operator))

是否可以在条件表达式中声明变量？

例如：下面的代码返回语法错误（因为我在条件表达式中声明了变量x？）。

var a = document.getElementById("userData"); var d = a.value; function() { (d.length>15)?( alert("your input was too long")):( var x = parseInt(d).toString(2), a.value=x ); }

显然，这可以通过简单地添加var x; 在声明之外，但是可以在这里声明变量吗？

Is it possible to declare the variable within a conditional expression?

for example: The code below return a syntax error (because I've declared the variable x within the conditional expression?).

var a = document.getElementById("userData"); var d = a.value; function() { (d.length>15)?( alert("your input was too long")):( var x = parseInt(d).toString(2), a.value=x ); }

obviously this can be fixed by simply adding var x; outside the statement, but is it possible for variables to be declared here?

最满意答案

是否可以在条件表达式中声明变量？

编号var是一个语句， 条件表达式的操作数是表达式。 语言语法不允许它。 值得庆幸的。

Is it possible to declare the variable within a conditional expression?

No. var is a statement, and the operands to a conditional expression are expressions. The language grammar doesn't allow it. Thankfully.