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JavaScript · 22 Exporting JSON with Blob
Series contents · Technology map
Stage: Integrating and verifying the experiment log · Editable example · Storage ID: javascript-step-22
Goals and learning outcomes
- The exported file contains 3 notes and a version value.
- Every generated object URL has a cleanup path.
Prerequisites
The work and experiment records from Unit 21, “FormData and Domain Validation”
Key concepts and explanations
Serialization
JSON.stringify converts data into a string. Functions and undefined are not preserved in the way you might expect.
Object URLs
A Blob URL refers to the generated file data. Release it with revokeObjectURL when you have finished using it.
Practice setup
First check the execution scope guidance on the example screen. The following environment is for extending the assignment in a separate project. Implement it yourself in a separate local project and check it with browser developer tools. In a separate folder, connect your practice JS from index.html using script type="module" and open it through a local HTTP server. Use the Console, Network, and Elements panels.
The linked example is a starting point. It does not implement every task below. Complete work beyond its supported scope in a separate project.
Practice tasks
- In export.js, prepare 3 notes and titles containing Korean characters and line breaks.
- Create a Blob containing the notes and schemaVersion, and save notes.json using a download link.
- Run with 3 notes and titles containing Korean characters and line breaks. Results to check: The exported file contains 3 notes and a version value. Every generated object URL has a cleanup path. Record expected and actual results separately.
Variables to observe
| Variable | Baseline | Change | Expected change / hypothesis |
|---|---|---|---|
| Title | English text | Korean characters and line breaks | Hypothesis before running: The restored string will match the original. Keep the other conditions fixed and record the actual result separately after running. |
Predictions in this table are not measured results. Change one condition at a time and record why the actual result differs.
Completion criteria
- The exported file contains 3 notes and a version value.
- Every generated object URL has a cleanup path.
Self-check
- Which values disappear during serialization?
- What happens if the URL is released too early?
Official references
Linked example and execution scope
Example source · Runtime environments and limits
Compare the editable inputs with actual browser execution results.
Source code and records are not overwritten automatically. Resetting an existing example also preserves your notes.
Next learning
Previous: FormData and Domain Validation · Next: File Import and Structure Validation