browser.date input format assumption

browser.date-input-format-assumption

Rule ID: browser.date-input-format-assumption Severity: ERROR Category: browser Target Standards: HTML Living Standard Section 4.10.5.1.7 (Date State - type=date), W3C RFC 3339 / ISO 8601 Normative Date Representation (YYYY-MM-DD)

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1. Overview & Core Invariant

Prohibits localized string splitting assumptions on HTML5 date input values in favor of normative ISO 8601 parsing

Core Invariant:

"Native values are guaranteed by W3C specification to be serialized strictly as ISO 8601 (YYYY-MM-DD). Code must not split values by localized delimiters ('/' or '.')."

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2. Technical Grounding & Engine Realities

While the browser UI may render localized date pickers according to OS settings (e.g., DD/MM/YYYY in Indonesia/UK, MM/DD/YYYY in US), the programmatic 'element.value' is ALWAYS serialized in ISO 8601 format ('YYYY-MM-DD').

Splitting by '/' causes catastrophic silent failures because the delimiter never exists in 'element.value'.

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3. Vulnerability & Risk Taxonomy

Risk Vector	Severity	Impact
Silent Date Parsing Failure	HIGH	Splitting ISO 8601 date string by '/' returns an array of length 1, corrupting day, month, and year data sent to APIs.
Cross-Locale Form Submission Corruption	HIGH	User birth dates, appointment bookings, or legal document dates are stored as NaN, undefined, or incorrect epochs.

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4. Non-Compliant Code Patterns (Bad Examples)

TSX (Splitting native date input value by '/' based on UI display assumption):

<input
  type="date"
  onChange={(e) => {
    // BUG: e.target.value is '2026-09-06'. Splitting by '/' fails!
    const [day, month, year] = e.target.value.split('/');
    saveDate(day, month, year);
  }}
/>

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5. Compliant Implementation Patterns (Good Examples)

TSX (Splitting native date input by normative ISO 8601 dash delimiter or using valueAsDate):

<input
  type="date"
  onChange={(e) => {
    // Correct: ISO 8601 format YYYY-MM-DD
    const [year, month, day] = e.target.value.split('-');
    saveDate(day, month, year);
  }}
/>

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6. Detection & Verification Pipeline (How The Rule Evaluates Code)

This rule evaluates source code through the standard AST inspection pipeline:

flowchart TD
    Node["AST Node (Astro / TSX element)"] --> Inspect["1. Inspect Element & Attributes"]
    Inspect --> Invariant{"2. Evaluate Rule Invariant"}
    Invariant -- "Compliant" --> Safe["Pass"]
    Invariant -- "Non-Compliant" --> IgnoreCheck{"3. Check charites:ignore directive"}
    IgnoreCheck -- "Ignored" --> Safe
    IgnoreCheck -- "Not Ignored" --> Diag["4. Emit Diagnostic: browser.date-input-format-assumption"]

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Step-by-Step Evaluation:

1. AST Traversal: Visits normalized ir.Node structures during AST streaming.
2. Invariant Check: Compares node attributes against rule invariants.
3. Directive Suppression Check: Honors inline charites:ignore browser.date-input-format-assumption directives.
4. Diagnostic Emission: Emits compiler-grade diagnostic on invariant violation.

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7. Verification & Test Harness (How The Test Works: 1-SSOT Tri-Corpus)

This rule is rigorously tested and validated across the canonical 1-SSOT Tri-Corpus in tests/correctness/browser.date-input-format-assumption/:

flowchart TD
    subgraph GoldenCorpus ["1-SSOT Tri-Corpus Test Matrix for browser.date-input-format-assumption"]
        subgraph P ["Positive Corpus (tests/correctness/browser.date-input-format-assumption/positive/)"]
            P1["P1: Obvious Direct Violation"]
            P2["P2: Indirect / Variant Concatenation"]
            P3["P3: Helper / clsx / cn Wrapper"]
            P4["P4: Deeply Nested Elements"]
            P5["P5: Aliased Imports / Re-exports"]
        end
        subgraph N ["Negative Corpus (tests/correctness/browser.date-input-format-assumption/negative/)"]
            N1["N1: Valid Design Tokens"]
            N2["N2: Explicit charites:ignore Directive"]
            N3["N3: Third-Party / Vendor Components"]
            N4["N4: Clean Semantic HTML"]
            N5["N5: Untokenized Custom Values (Banana Test)"]
        end
        subgraph A ["Adversarial Corpus (tests/correctness/browser.date-input-format-assumption/adversarial/)"]
            A1["A1: Template Literal Interpolations"]
            A2["A2: Ternary Conditional Expressions"]
            A3["A3: Spread Properties & Dynamic Overrides"]
            A4["A4: Dynamic Object Class Syntax"]
            A5["A5: Shadowed Variable Identifiers"]
            A6["A6: Nested Closures & HOC Wrappers"]
            A7["A7: Obfuscated Classes & Cyclic Tokens"]
        end
    end

    P --> TestRunner["Automated Runner (rule_test.go)"]
    N --> TestRunner
    A --> TestRunner
    TestRunner --> Gates["Quality Gates: Zero Panic, Zero False-Positive, Zero Bypass"]

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• Positive Fixtures (P1-P5): Verified to trigger diagnostics at exact lines and column spans.
• Negative Fixtures (N1-N5): Verified to produce zero diagnostics on valid tokens and legitimate exemptions.
• Adversarial Fixtures (A1-A7): Verified to prevent evasion across dynamic expressions, string interpolations, and cyclic references.

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8. How to Suppress (Ignore Directives)

If this pattern is required for an intentional exception, suppress the diagnostic using the canonical Charites Rule ID:

<!-- charites:ignore browser.date-input-format-assumption intentional exception -->

// charites:ignore browser.date-input-format-assumption intentional exception

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9. Configuration Reference (charites.yaml)

rules:
  browser.date-input-format-assumption:
    severity: error # error | warn | info | off