javascript - 为什么 typeof 字符串在 js 中显示“未定义”

Question

<script>
var pimitiveString1 = "This is a primitive string";    
var pimitiveString2 = String("This is a primitive string");    
alert(typeof primitiveString1);
alert(typeof primitiveString2);  
</script>

问题：

它显示“未定义”，为什么它不是“字符串”？pimitiveString1 和 pimitiveString2 是字符串类型，对吧？

Answer 1

拼写错误

var primitiveString1 = "This is a primitive string";    
var primitiveString2 = String("This is a primitive string");    
alert(typeof primitiveString1);
alert(typeof primitiveString2);  

Answer 2

那是因为错字：

pimitiveString1v/sprimitiveString1

alert(typeof pimitiveString1); //This will alert string
alert(typeof pimitiveString2);  // This will be a string

Answer 3

您String错误地调用了构造函数。正确的方法是

<script>
var primitiveString1 = "This is a primitive string";    
var primitiveString2 = new String("This is a primitive string");    
alert(typeof primitiveString1);
alert(typeof primitiveString2);  
</script>

您的标识符中还有一个typo。它应该var primitiveString1代替var pimitiveString1