Cell value inference

inferCellType, escape helpers, error code constants.

5 exports from 3 source files

Escape

escapeCellString function

Escape a string for safe storage in an OOXML cell. An underscore that opens an _xHHHH_ sequence becomes _x005F_; illegal codepoints are replaced with their _xHHHH_ representation. unescapeCellString recovers the input for any string.

function escapeCellString(s: string): string

Parameters

Name	Type	Description
`s`	`string`

Returns

string

unescapeCellString function

src/utils/escape.ts:62

Inverse of escapeCellString. Looking from left to right we replace any _xHHHH_ sequence with the corresponding code unit; the protected _x005F_ becomes a literal underscore which the subsequent replacements skip safely (replace's regex is non-overlapping).

function unescapeCellString(s: string): string

Parameters

Name	Type	Description
`s`	`string`

Returns

string

Inference

src/utils/inference.ts

inferCellType function

src/utils/inference.ts:67

Infer the cell t attribute for a runtime value.

- boolean → 'b' - number → 'n' (incl. integer numerics; date inference is left to the caller because Excel decides on type via the cell's number format, not the raw value) - Date → 'd' - string starting with = → 'f' (formula), except a lone '=', which is 's' - string in ERROR_CODES → 'e' - any other string → 's' - null / undefined → 'n' (empty)

Throws nothing: 'n' is the no-information fallback. It reports the spelling and nothing more, so 'f' is not a promise that the formula constructors will accept the text: '==A1' classifies as 'f' and setFormula rejects it.

function inferCellType(value: unknown): CellDataType

Parameters

Name	Type	Description
`value`	`unknown`

Returns

CellDataType

ERROR_CODES const

src/utils/inference.ts:28

Excel error tokens this library knows by name. On a write, a string outside this set is text, so the set is what inferCellType and makeErrorValue accept as an error.

It is not a closed description of the format: Excel has added nine tokens since 2018 and can add more, so a t="e" cell read out of a file keeps whatever token it carries, listed here or not, as long as the token is shaped like one (isExcelErrorToken in ./cell-error.js).

Adding a token here changes what a write does with the matching string: inferCellType and bindValue turn it into an error value instead of text, and makeErrorValue starts accepting it.

const ERROR_CODES: ReadonlySet<string>

Css

src/utils/css.ts

cssRecordToInlineStyle function

src/utils/css.ts:25

Serialize a CSS-property record to an inline-style declaration string (prop1: val1; prop2: val2). Properties are alphabetised so the output is deterministic across runs.

- Empty record returns ''. - Empty-string values are skipped (treat as "unset"). - Values containing ; are dropped — they would terminate the declaration early and risk attribute-injection in style="…" contexts. Callers should pre-escape user data; this is a defensive last line.

The returned string is suitable for direct interpolation into an HTML style="…" attribute *after* the usual attribute-value HTML escaping (no & / " injection here — this only guards against stray semicolons).

function cssRecordToInlineStyle(record: Record<string, string> | undefined): string

Parameters

Name	Type	Description
`record`	`Record<string, string> \| undefined`

Returns

string