I have created REST API using node.js.since the API consumer is not correctly populating the object & some of the object attributes are coming "undefined" and sometimes undefined.
I have added a request interceptor that rejects API request if the required request parameters are missing
this is how my code looks like today. I just want to check if there is any better way to handle it.
(!variable_name || variable_name === 'undefined')
The most specific and self-explaining way is:
foo === undefined || foo === 'undefined'
While
!foo || foo === 'undefined'
condition is equivalent to
foo === undefined || foo === null || foo === false || foo === '' || foo === 0 || foo === NaN || foo === 'undefined'
This may result in false positive for any listed falsy value. If this is the case, !foo shouldn't be used.
A shorter way is to coerce foo to a string:
'' + foo === 'undefined'
This may result in false positive for any object that has toString() returning undefined. If this is undesirable, it shouldn't be used.
This is a workaround to fix a problem that shouldn't exist in the first place. undefined shouldn't be indistinguishable from 'undefined' string because this way there's no way to tell if it was originally 'undefined' string ('undefined' is a word) or undefined that was accidentally stringified.
"undefined" as it is => a string.
undefined or 'undefined' string because it was supplied by API this way. I agree that the distinction between those two just complicates everything at this point.'undefined' string that was erroneously created.
'undefined'instead ofundefined!variablemeans it could be 0, empty string, undefined, null (and I'm probably forgetting others). you can check for exact equality to undefined by sayingfoo === undefined. note the three equals. the string 'undefined' is just a word, you may as well have said 'bar' there.||instead of!!I am doing likeand getting a syntax error in the console no doubtwindowin an unknown context. If you know you have a variable available,typeofis not necessary.