JavaScript tools
Format JSON safely: know what parsing can change
Format a JSON response with JavaScript, handle invalid input and spot cases where parsing can lose information.
Read guideSmall tools for the things between the code.
Practical JavaScript and TypeScript tools, with notes on what they can and cannot tell you. Start with a JSON sample.
JSON to TypeScript
Paste JSON to sketch a TypeScript type. It describes this sample, not every response your API might return.
This type describes one sample. Review optional fields and other possible responses before using it. It does not validate API responses.
Practical guides
All guidesTypeScript
TypeScript narrowing and satisfies solve different problems
Use runtime guards to narrow uncertain values and satisfies to check configurations without confusing the two.
Read guideDates and data
Format dates with an explicit time zone
Show one JavaScript timestamp in London and Paris, keep UTC output separate and test seasonal differences.
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