How to Fix: SyntaxError with Middle Dot (U+30FB) as Object Key in Older iOS Safari Versions

Older iOS Safari versions can crash on code that looks perfectly valid in modern browsers: an object key containing the Middle Dot character (U+30FB) may trigger a SyntaxError during parsing, which breaks the page before your application even runs. In newer Next.js versions, this usually appears when the emitted client-side JavaScript preserves that character in an unquoted property name, exposing a compatibility gap in legacy WebKit engines.

If your reproduction uses an object like {・: "value"} or a similar identifier-based property name, the problem is not your app logic. The issue is that some older Safari builds do not fully support parsing that Unicode character as part of an IdentifierName in JavaScript source, even though modern engines do.

Understanding the Root Cause

This bug sits at the intersection of JavaScript parsing, Unicode identifiers, and browser compatibility.

In JavaScript, object property keys can be written in multiple ways:

const ok1 = { name: "value" }        // simple identifier key
const ok2 = { "name": "value" }      // string literal key
const maybeProblematic = { ・: "value" } // unquoted Unicode identifier key

Modern JavaScript engines can parse many Unicode characters in identifiers according to the ECMAScript spec. However, older iOS Safari versions use older WebKit parser behavior and may reject specific characters such as U+30FB when they appear as an unquoted object key.

That means the failure happens at parse time, not runtime. So:

• The page can fail before React renders anything.
• try/catch will not help because the script never finishes parsing.
• The error may appear only on older iPhones or iPads, making it easy to miss during desktop testing.

Why does this show up in Next.js 14.2.5+? In practice, newer build pipelines, minification paths, or emitted module output can preserve object literal keys in a way that leaves the legacy parser exposed to the unsupported character. The framework is not inventing the bug; it is surfacing a browser parsing limitation.

The safest takeaway is simple: do not rely on unquoted non-ASCII object keys if you need legacy Safari support.

Step-by-Step Solution

The most reliable fix is to convert the problematic key into a quoted string key or replace it with an ASCII-safe identifier.

1. Find unquoted Unicode property keys

Look for object literals, destructuring patterns, exported constants, or config maps that contain non-ASCII characters as bare identifiers.

// Problematic for older iOS Safari
const labels = {
  ・: "separator",
}

2. Quote the key explicitly

Using a string literal avoids the parser ambiguity in older engines.

// Safe
const labels = {
  "・": "separator",
}

This works because string-literal property names are parsed differently from identifier-based property names.

3. Prefer ASCII internal keys when possible

If the key is only used internally, use a stable ASCII key and keep the Unicode character in the value.

// Even safer and easier to maintain
const labels = {
  middleDot: "・",
}

This is usually the best choice for shared codebases, analytics payloads, serialization, and cross-browser UI logic.

4. Update bracket access if needed

If your code references the property directly, switch to bracket notation for string keys.

const labels = {
  "・": "separator",
}

console.log(labels["・"])

If you rename the key to ASCII, update all access sites:

const labels = {
  middleDot: "separator",
}

console.log(labels.middleDot)

5. Check generated constants, dictionaries, and localization files

This issue often appears in mapping objects for UI labels, token dictionaries, or input method data.

// Risky pattern
export const punctuationMap = {
  ・: "middle-dot",
  。: "full-stop",
}

// Safer pattern
export const punctuationMap = {
  "・": "middle-dot",
  "。": "full-stop",
}

6. Verify on affected Safari versions

After the fix, test on the actual failing target if possible. Use BrowserStack, Sauce Labs, or a physical device running an older iOS Safari build. The key signal is that the page now loads without a parse-time SyntaxError.

7. Add a preventive lint or code review rule

If your team supports older Apple devices, prevent similar regressions by flagging bare non-ASCII object keys during review or static analysis.

// Team convention example
// Avoid:
const map = { ・: true }

// Prefer:
const map = { "・": true }
// or
const map = { middleDot: true }

Practical before/after example in Next.js

// before
export const symbols = {
  ・: {
    label: "Middle Dot",
    category: "punctuation",
  },
}

// after
export const symbols = {
  "・": {
    label: "Middle Dot",
    category: "punctuation",
  },
}

If the key is imported across multiple files, search for property access patterns and update them consistently.

Common Edge Cases

• Destructuring can also fail: syntax like const { ・ } = obj may be rejected by older Safari for the same parser reason. Use const value = obj["・"] instead.
• Minified bundles may hide the source: the production error can point to compiled code instead of your original file. Search your source for bare Unicode keys and generated object literals.
• JSON is usually not the problem: {"・":"value"} is valid JSON because keys are quoted. The issue is specifically with JavaScript source syntax.
• Computed properties are different: { ["・"]: "value" } is typically safe, though a plain quoted key is simpler and clearer.
• Other Unicode characters may behave similarly: if one punctuation character fails, do not assume others are safe on legacy engines. Quoting all non-ASCII keys is the safer policy.
• Third-party packages can trigger it: if the bug remains after your changes, inspect dependencies or generated code that ships to the browser.
• Server-side rendering may mask the issue: the initial HTML can render, but hydration or client navigation can fail once the problematic bundle is parsed in Safari.

FAQ

Why does this work in Chrome and fail in older iOS Safari?

Because modern engines such as V8 and newer WebKit versions support a broader and more standards-aligned set of Unicode identifier rules. Older iOS Safari builds use an outdated parser that rejects some characters, including U+30FB in this context.

Is this a Next.js bug or a Safari bug?

It is primarily a Safari compatibility issue, but Next.js can expose it depending on how your source code is bundled and emitted. The framework does not fix invalid parsing behavior in legacy browsers automatically, so the application code should avoid risky syntax.

What is the safest long-term fix?

The safest approach is to use ASCII keys for internal objects and reserve Unicode characters for values shown to users. If you must keep the Unicode key, always write it as a quoted string property.

In short, the production-grade fix for this issue is to stop using U+30FB as an unquoted object key in browser-delivered JavaScript. Quote the key or rename it to ASCII, retest on older iOS Safari, and you will eliminate the parse-time SyntaxError without changing your application behavior.