◆ JavaScript

Determine if variable is null or undefined

This is real work, not a feature someone invented — it comes from real job ads and real questions people asked. Below are four ready AI prompts: get it done, make it easy for the next person to say yes to, work out the right move when you are stuck, and stop it coming back.

4prompts

The same task, four prompts

today's deadline · the next reviewer · the stuck moment · the pattern
AExecute — do the immediate taskCheck if this `userProfile` variable is either null or undefined before I try to access its…+
Check if this `userProfile` variable is either null or undefined before I try to access its properties. I need to avoid a runtime error when rendering the user's dashboard.
when the reply comes backPush once: ask it to sharpen the weakest part, and to say what it assumed. Helpful?
BImprove — make it easier to acceptBefore I use this `configSetting` variable, make sure it handles both `null` and `undefined`…+
Before I use this `configSetting` variable, make sure it handles both `null` and `undefined` gracefully. I'm seeing inconsistent data from the backend and need to prevent the UI from breaking if a setting is missing.
when the reply comes backPush once: ask it to sharpen the weakest part, and to say what it assumed. Helpful?
CDecide — diagnose the stuck momentThe new user profile API is live, and I'm trying to display the user's email. Sometimes the…+
The API just returned a `userData` object, but I'm not sure if the `email` field will always be there or if it might be `null` or `undefined`.
The new user profile API is live, and I'm trying to display the user's email. Sometimes the `email` field is missing entirely, other times it's explicitly `null`. I'm afraid of a crash if I just try to access `userData.email`. What's the most robust way to check for both `null` and `undefined` before displaying it, and what's the best next move if it's not present?
when the reply comes backPush once: ask it to sharpen the weakest part, and to say what it assumed. Helpful?
DBecome — change the patternI'm constantly chasing down bugs where properties are accessed on `null` or `undefined`…+
I keep getting runtime errors in the UI because I'm not consistently checking for `null` or `undefined` values from API responses.
I'm constantly chasing down bugs where properties are accessed on `null` or `undefined` objects, especially after new API deployments. It feels like I'm always adding last-minute checks. What habit should I change to proactively handle these missing values across my codebase, so I stop getting these errors?
when the reply comes backPush once: ask it to sharpen the weakest part, and to say what it assumed. Helpful?

Questions people actually ask

honest answers, no sign-up

Every task here was seen in the real world. Someone doing the job named it, a real job ad asked for it, or a lot of people asked about it online.

If nothing real showed a task, it is not on the page. That is the whole rule.

They are the same job approached four ways, because what you need depends on where you are.

Get it done today. Make it easy for the next person to say yes to. Work out the right move when you are stuck. Learn the pattern so the job stops coming back.

For most of these jobs it can carry the heavy thinking - draft it, sort it, check it, rehearse it with you.

It cannot sit in your chair, take the blame when a number is wrong, or notice what nobody wrote down. Let it do the first 80%. Keep the last 20% that is truly yours.

No. Copy any prompt and paste it into the AI you already use. No account, no score, no wall in the way.

Any of them. The prompts describe the work rather than naming a product, so they are not tied to one assistant.

That is also why they keep working when you switch.

Change it freely. Every prompt is a starting line, not a rule.

Put in your real numbers, your real names and your real deadline. The more you make it yours, the better the answer comes back.

The tasks come from real job ads, published job data and the questions people ask in public forums.

The steps come from JavaScript's own documentation, with practitioner sources for the traps the manual does not mention.

Push once. Ask it to sharpen the weakest part and to say what it assumed.

Most wrong answers come from a missing detail rather than a bad prompt - tell it the thing it could not know.