在多个条件中使用？ ：javascript中的语句

Question

需要检查三个条件并根据条件为变量赋值。

if(a =="z1"){ 
    b = "one"; 
} else if(a =="z2"){ 
    b = "two"; 
} else if(a =="z3"){ 
    b = "three"; 
} 

是否可以在JavaScript中使用？ ：声明使其成为单行代码

Answer 1

是的，您可以使用将其转换为Conditional(ternary) operator。

var a = "z3"; 
 
var b = a == "z1" ? "one" : a == "z2" ? "two" : a == "z3" ? "three" : "" ; 
 

 
console.log(b);

---

FYI：为了更好的可读性，我会建议使用 if...else语句或使用 switch声明。尽管在复杂操作的情况下需要使用括号来嵌套三元运算符，以避免出现问题。

Answer 2

var b = (a =="z1") ? "one" : ((a =="z2") ?"two":(a =="z3")?"three":null); 

不要忘了，阅读这篇文章很难。 如果使用一个if else块，则可以使用。

Answer 3

你可以做这样的事情：？？？

B =（A == “Z1”， “一个” :(一== “Z2”， “二” :(一== “Z3”“三“：！未定义）））

Answer 4

var b = a == "z1" ? "one" : (a == "z2" ? "two" : (a == "z3" ? "three" : undefined)) ; 

a = "z1" 
 

 
alert(a == "z1" ? "one" : (a == "z2" ? "two" : (a == "z3" ? "three" : undefined))); 
 

 
a = "z2" 
 

 
alert(a == "z1" ? "one" : (a == "z2" ? "two" : (a == "z3" ? "three" : undefined))); 
 

 
a = "z3" 
 

 
alert(a == "z1" ? "one" : (a == "z2" ? "two" : (a == "z3" ? "three" : undefined))); 
 

 
a = "z4" 
 

 
alert(a == "z1" ? "one" : (a == "z2" ? "two" : (a == "z3" ? "three" : undefined)));