Concise way of handling javascript null objects -


what want achieve clean code several possible null returns i'm not returning in more 1 place, code easy follow , not nested nightmare. example consider 

var toplevel = testdata['key'];//testdata['key'] may null var nextlevel = toplevel['subkey']; //toplevel['subkey'] may null var subsublevel = ...

my initial thoughts 

var toplevel = testdata['key'] || 'error';

this @ least stop "cannot x of null" errors i'll have block @ end i'll need check if each of these vars error , if return null , provide appropriate error message (probably associative object).

does have smarter, more concise way of achieving same end result?

i'd javascript's curiously-powerful && operator (the cousin of curiously-powerful || operator you're using):

var toplevel = testdata['key']; var nextlevel = toplevel && toplevel['subkey']; // ...

if toplevel falsey (null, undefined, , on), nextlevel falsey value (the left-hand operand); if not, right-hand operand evaluated , nextlevel receives value of that. using these kinds of guards, can keep going long want.

var toplevel = testdata['key']; var nextlevel = toplevel && toplevel['subkey']; var nextnextlevel = nextlevel && nextlevel['key3']; var nextnextnextlevel = nextnextlevel && nextnextlevel['key4'];

this handy when you're expecting object reference, null, or undefined.


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