JavaScript array to number
Possible Duplicate:
Can you explain why ++[[]][+[]]+[+[]] = 10
I'm wondering something for few days...I know that unary plus in JavaScript first converts it's operand to Number. I'm applying + to an empty array and I get the following result:
+[] == 0
When I do this:
+[1] == 1
But:
+[1,2] == NaN
The last two things are almost clear but why the empty array is 0?! Is this connected with:
[] == false
Some times ECMAScript makes me wonder a lot...
alert([![]+[]][+[]][+[]]+[![]+[]][+[]][+!+[]]+[!+[]+[]][+![]][+![]]+[![]+[]][+[]][+!+[]]+[![]+[]][+[]][+!+[]+!+[]]+' '+(![]+[])[+[]]+(![]+[])[+!+[]]+([![]]+[][[]])[+!+[]+[+[]]]+(![]+[])[!+[]+!+[]]);
Best regards!
The stringified form of the empty Array is an empty string:
> [].toString()
""
The unary operator + converts to Number objects, so, it converts an empty string to 0 :
> Number("")
0
This explains why +[] == 0 is true.
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