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1. Expand operator
The expansion operator converts the array into individual parameters , therefore arr3 And arr1 Are two different array objects

1.1 The expansion operator can also take out all the traversable properties of the object , Copy to current object .

2. Object literal syntax extension start
The attribute name contains special characters or Chinese , Or you need to calculate the attribute name , Only square brackets can be used

3. Deconstruct assignment start

3.1 If the variable has been declared before , Then you want to assign values to variables using deconstruction Syntax , Then you need to wrap the entire deconstruction assignment statement with parentheses

3.2 Property name ： Local variable name

3.3

here category in ,name The value of category, therefore category The value of becomes “web front end ”

3.4 An array of deconstruction

3.5

The comma here , It refers to the front “Vue”, therefore language2 The corresponding is "React".

I wanted to send it yesterday morning , As a result, the leader suddenly appeared , I didn't send it .
Ready for work , I'm going to eat with my friends later. Hey, hey , I haven't eaten it for a long time , After eating, go home and see the cat in the pet shop downstairs , You can buy a cat right away ！！！
Study hard ！ Make money with great effort ！ Miao Miao Zi ！！！