javascript - Inconsistency in JS console when adding arrays and objects -


i don't want ask why [] + [] gives empty string, or on, can't change it. , reason design of language.

my question following inconsistency, noticed in chrome , ff firebug js consoles:

{} + []; // outputs 0 console.log({} + []); // outputs [object object] var c = {} + []; console.log(c); // outputs [object object]

i understand expression returns value, , see in console output. why return value changes, when assigned variable or output using console.log()?

does mean mentioned consoles buggy?

is there better explanation stating this way it's done?

in first example, block, equivalent running code (the plus in front of array literal converts number):

{}; +[]; // 0

however, in console.log code, considered expression, in fact object literal. can pass expressions functions, same.

function a(b) {return b;} a({}+[]); // "[object object]"

the addition operation converts them string, that's why "[object object]".


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