JavaScript undefined defined区别的相关内容

文章 2023-11-16 来自：开发者社区

JavaScript中undefined和not defined的区别

在JavaScript中，undefined和not defined是两个不同的概念。undefined：表示一个变量已经声明了，但是它的值还没有被设置。例如：let x; console.log(x); // undefinednot defined：表示一个变量还没有被声明。例如：console.log(y); // Uncaught ReferenceError: y is not def....

文章 2023-11-06 来自：开发者社区

JavaScript中undefined和not defined的区别

在JavaScript中，"undefined"和"not defined"有着不同的含义和用法。"undefined"：这是JavaScript中一个特殊的值，表示变量没有被赋值，或者对象的属性不存在。当我们尝试访问一个未被赋值或者不存在的属性时，会得到这个值。例如：let a; console.log(a); // 输出：undefined let obj = {}; console.lo.....

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更新时间 2023-11-24 14:17:22

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