JSON / CORE CONCEPTS
Strings, numbers, booleans, null, arrays, and objects
Learn how strings, numbers, booleans, null, arrays, and objects works in JSON, why the underlying model matters, and how to apply it in a small program without hiding important trade-offs.
What you will learn
- Explain strings in JSON using the correct mental model
- Trace a focused JSON example and predict its result before execution
- Recognize a boundary case involving numbers and handle it deliberately
Understanding Strings, numbers, booleans, null, arrays, and objects
Strings, numbers, booleans, null, arrays, and objects belongs to the practical core of JSON. Start by identifying the values or state involved and the rule that connects the input to the result.
Trace the example one operation at a time. Keep strings visible in the code rather than hiding it behind an abstraction before the behavior is understood.
Test a normal case and a boundary case. The difference between the prediction and the observed result is the most useful signal for deciding what to review next.
Strings, numbers, booleans, null, arrays, and objects is a defining part of practical JSON work. Start by identifying the data or state involved, then trace the operation that changes or interprets it. Pay attention to the rules JSON applies at this boundary, because those rules explain both the useful behavior and the common failure modes. This lesson keeps the example deliberately small, then connects it to traversal, comparison, and json pointer so the ideas form a coherent progression rather than a list of isolated syntax facts.
Worked examples
Strings, numbers, booleans, null, arrays, and objects example
A focused JSON example for strings.
{
"lesson": 4,
"topic": "strings",
"track": "JSON",
"boundaryCase": true
}Example explained
Line 1Identify where strings appears in the JSON example and name the data it operates on.
Line 2Trace the relevant JSON rule one operation at a time, recording any state, type, or control-flow change.
Line 3Change one input or boundary condition, predict the result, and compare that prediction with the documented outcome.
Important notes
Keep the first strings example small enough to trace completely.
Use the normal JSON toolchain or browser workspace to compare the actual result with your prediction.
Common mistakes
Treating strings as punctuation to memorize instead of a JSON behavior to reason about.
Ignoring numbers until it appears in production data or a larger program.
Try it yourself
Change, predict, then run
Create a small JSON example that demonstrates strings. Add a normal case and a boundary case, write down the expected result for each, then explain which JSON rule produces that result. Lesson 4 should remain small enough to trace without guessing.
Open JSON workspaceCheck your understanding
What is the best first step when working with strings?
- Identify the data and predict the result
- Add more abstraction immediately
- Ignore boundary cases
- Memorize punctuation only
Show answer
A clear input, operation, and predicted result create a testable mental model.