A pitfall of object questions to understand Javascript objects,

A pitfall of object questions to understand Javascript objects,

The example in this article is mainly intended to attract understanding and attention to Javascript objects. In fact, it is a kind of challenge during the interview, and it is rarely used in actual projects. However, in order to improve the vigilance, let's look at this example:

Code name

Var first = {}; var second = {k: "second"}; var third = {k: "third"}; first [second] = 100; first [third] = 200; console. log (first [second]) // What will be output here?

If you want to answer this question by yourself, I will not explain it later.

What results will be output here? Most people may think that the result is 100, the question is wrong, or the result is 200.

The final result is 200..

Why?Because second and third are both objects and [object], therefore, first [second] is equivalent to first [[object]. Similarly, first [third] is equivalent to first [object]. Therefore, the final result can be first ["[object ].] "], in this example, the expression is assigned a value twice, so the final result is 200.

So in javascript, we need to pay attention to a lot of details, maybe those interviewers, who do not know what interview questions are, and try their best to answer these traps. However, we just need to build a solid foundation, so we are not afraid of anything! I will continue to explain some questions in the future!

Through a simple example, we have aroused everyone's thinking and provided a lot of inspiration for everyone to learn javascript objects. I hope you will gain some benefits.

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