问题
I was recently alarmed to discover the following:
> {}+[]
0
> ({}+[])
"[object Object]"
> {}+[]+1
1
> ({}+[])+1
'[object Object]1'
> {}+[] == ({}+[])
false
Why does wrapping something in parenthesis change its type?
回答1:
{} + [] is an empty block followed by a an array with a unary + operator, which is essentially, which is +[] which is 0,
({} + []) is a literal object plus a literal array, both get converted into strings, the string value of an object is "[object Object]" plus the string value of an empty array which is "", hence the result you see.
来源：https://stackoverflow.com/questions/36409966/why-is-different-from