理解Javascript中的双括号操作

Question

What does [1,2,3][1,2] means in Javascript? I do not understand what its supposed to do, and i have no clue how could i google such thing.

Any ideas?

I assume this is quite the newbie question, please forgive my ignorance.

Answer 1

• [1,2,3] is an Array literal
• <obj>[p] is the bracket notation for property access
• 1, 2 is a comma operator expression that evaluates to 2

So the [1,2,3][1,2] as a whole accesses the index 2 of the array, and yields 3 .