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Javascript 为什么字符串类型在js中显示为“未定义”_Javascript - Fatal编程技术网

Javascript 为什么字符串类型在js中显示为“未定义”

Javascript 为什么字符串类型在js中显示为“未定义”,javascript,Javascript,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,对吗?拼写错误 <script> var pimitiveString1 = "This is a primitive string"; var pimitiveString2 = String("This is a primitive string"); alert(typeof primitiveString1); alert(typeof

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,对吗?

拼写错误

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

这是因为打字错误:

pimitiveString1 v/s primitiveString1

您正在错误地调用字符串构造函数。正确的方法是

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

此外,您的标识符中也有输入错误。它应该是var primitiveString1,而不是var pimitiveString1

-1:typeof Stringfoo是'string',而不是'object'新字符串和字符串做不同的事情。我不确定OP是在尝试创建字符串对象还是字符串原语。-1:StringThis is a primitive string实际上是一个字符串。新字符串与String@Blender你在哪里读到OP想要使用字符串构造函数的问题?@Nirk:我在做一个assumption@Nirk这个答案并没有错,这比另外两个答案要好,因为这两个答案只是指出了拼写错误。我给的是+1
alert(typeof pimitiveString1); //This will alert string
alert(typeof pimitiveString2);  // This will be a string
<script>
var primitiveString1 = "This is a primitive string";    
var primitiveString2 = new String("This is a primitive string");    
alert(typeof primitiveString1);
alert(typeof primitiveString2);  
</script>