Typeof !== "undefined" vs. != null
Use typeof variable !== "undefined"
to ensure variable
is not undefined
. The check variable != null
addresses when it's neither null
nor undefined
but bears a risk with undeclared variables. To secure robustness, stick to using typeof
.
Example:
Safety measures for global identifiers
Using typeof
for undeclared variables
When dealing with global identifiers, typeof
is your safety net. It avoids throwing the ReferenceError
party nobody likes. With undefined
being a bit of a chameleon in JavaScript (it can be redefined), typeof
is your security agent against such identity crises.
Ensuring 'undefined' stays 'undefined'
If JavaScript was a heist movie, undefined
would be the diamond everyone tries to replace. Using an Immediately Invoked Function Expression (IIFE) or the void operator ensures undefined
remains undefined
.
Coding style considerations
Implications on coding style and analysis
Searching for clear signs in the maze that is JavaScript? Clarity and readability are keys to mastering the labyrinth. typeof input !== 'undefined'
is captain obvious, a clear and standard method for checking existence. However, null != input
might require a map and compass, potentially conflicting with style guidelines.
Keeping JavaScript environment in mind
Sure, you can use the window object instead of those pesky string comparisons. Sounds cooler, right?
But remember, assuming you are always in a browser environment is like thinking you are always on vacation. Don't forget about server-side JavaScript like Node.js!
Best practices for checking null or undefined
Checking for both undefined and null
Expecting a visit from an elusive variable (think optional function parameters)? null != input
is like an alarm system that catches both null
and undefined
—caught red-handed!
Encapsulate and conquer!
For ultimate protection, encapsulate your variable checks:
Choosing the most suitable techniques
Ensuring code maintainability
A titan of strength in the world of coding is resiliency and readability. Forget relying on devious global variables. Stand tall and make code maintainable with typeof
and IIFE.
Making the best choice
The best tool for the job depends on the task. typeof
for when existence is the question. null !=
for when you need to catch both null
and undefined
. Like picking between Batman and Superman, both get the job done, but your context will determine the best choice.
Was this article helpful?