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Add MimeType utility functions (#69)
This PR adds a comprehensive set of MIME type utility functions to the javascript-utils library. ## Functions Added - `isImageMimeType(mimeType?: string): boolean` - Check if MIME type is for images (image/*) - `isPdfMimeType(mimeType?: string): boolean` - Check if MIME type is for PDF files (application/pdf) - `isVideoMimeType(mimeType?: string): boolean` - Check if MIME type is for videos (video/*) - `isAudioMimeType(mimeType?: string): boolean` - Check if MIME type is for audio (audio/*) - `isTextMimeType(mimeType?: string): boolean` - Check if MIME type is for text (text/*) - `isApplicationMimeType(mimeType?: string): boolean` - Check if MIME type is for applications (application/*) ## Usage Examples ```typescript import { isImageMimeType, isPdfMimeType, isVideoMimeType } from '@neolution-ch/javascript-utils'; // Image types isImageMimeType('image/jpeg'); // true isImageMimeType('image/png'); // true isImageMimeType('video/mp4'); // false // PDF documents isPdfMimeType('application/pdf'); // true isPdfMimeType('image/jpeg'); // false // Video files isVideoMimeType('video/mp4'); // true isVideoMimeType('video/webm'); // true isVideoMimeType('audio/mp3'); // false ``` ## Key Features - **Robust input handling**: Gracefully handles null/undefined inputs (returns false) - **Case-insensitive**: MIME type checking works regardless of case - **Whitespace tolerant**: Automatically trims whitespace from inputs - **Format validation**: Ensures proper MIME type format (requires type/subtype pattern) - **Comprehensive testing**: 100% test coverage with extensive edge cases ## Implementation Details - Created `src/lib/mimeType.ts` with all utility functions - Created `src/lib/mimeType.spec.ts` with comprehensive test suite (102 test cases) - Added export to `src/index.ts` to make functions available - Follows existing library patterns for parameter validation and JSDoc documentation - Maintains 100% test coverage requirement ## Testing All tests pass including: - Input validation (null, undefined, non-strings) - Valid MIME type detection for each category - Case insensitivity verification - Whitespace handling - Invalid format rejection - Cross-category validation (ensuring image functions reject video types, etc.) Fixes #44. <!-- START COPILOT CODING AGENT TIPS --> --- 💬 Share your feedback on Copilot coding agent for the chance to win a $200 gift card! Click [here](https://survey.alchemer.com/s3/8343779/Copilot-Coding-agent) to start the survey. --------- Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com> Co-authored-by: neotrow <92933708+neotrow@users.noreply.github.com> Co-authored-by: drebrez <1611547+drebrez@users.noreply.github.com>
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‎CHANGELOG.md‎

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## [Unreleased]
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### Added
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- `isImageMimeType`, `isPdfMimeType`, `isVideoMimeType`, `isAudioMimeType`, `isTextMimeType`, and `isApplicationMimeType` MIME type utility functions
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## [1.4.0] - 2025-06-24
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### Added

‎src/index.ts‎

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@@ -4,6 +4,7 @@ export * from "./lib/date";
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export * from "./lib/enum";
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export * from "./lib/guid";
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export * from "./lib/localStorage";
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export * from "./lib/mimeType";
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export * from "./lib/number";
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export * from "./lib/object";
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export * from "./lib/string";

‎src/lib/mimeType.spec.ts‎

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import { isImageMimeType, isPdfMimeType, isVideoMimeType, isAudioMimeType, isTextMimeType, isApplicationMimeType } from "./mimeType";
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describe("mimeType tests", () => {
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// Common invalid inputs
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const invalidInputs: [string | null | undefined | number | Date, boolean][] = [
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[null as unknown as string, false],
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[undefined as unknown as string, false],
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[0 as unknown as string, false],
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[new Date() as unknown as string, false],
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["", false],
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[" ", false],
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["not-a-mime-type", false],
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];
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test.each([
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...invalidInputs,
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// Valid image MIME types
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["image/jpeg", true],
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["image/png", true],
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["image/gif", true],
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["image/webp", true],
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["image/svg+xml", true],
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["IMAGE/JPEG", true], // Case insensitive
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[" image/gif ", true], // Whitespace trimmed
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// Invalid cases
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["application/pdf", false],
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["text/plain", false],
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["video/mp4", false],
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["image", false],
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["image/", false],
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["/image", false],
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])("isImageMimeType", (mimeType, expected) => {
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expect(isImageMimeType(mimeType as string)).toBe(expected);
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});
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test.each([
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...invalidInputs,
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// Valid PDF MIME type
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["application/pdf", true],
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["APPLICATION/PDF", true], // Case insensitive
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[" application/pdf ", true], // Whitespace trimmed
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// Invalid cases
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["image/jpeg", false],
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["application/json", false],
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["pdf", false],
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["application/", false],
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])("isPdfMimeType", (mimeType, expected) => {
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expect(isPdfMimeType(mimeType as string)).toBe(expected);
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});
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test.each([
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...invalidInputs,
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// Valid video MIME types
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["video/mp4", true],
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["video/mpeg", true],
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["video/webm", true],
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["VIDEO/MP4", true], // Case insensitive
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[" video/webm ", true], // Whitespace trimmed
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// Invalid cases
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["image/jpeg", false],
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["audio/mp3", false],
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["video", false],
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["video/", false],
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["/video", false],
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])("isVideoMimeType", (mimeType, expected) => {
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expect(isVideoMimeType(mimeType as string)).toBe(expected);
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});
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test.each([
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...invalidInputs,
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// Valid audio MIME types
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["audio/mp3", true],
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["audio/mpeg", true],
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["audio/wav", true],
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["AUDIO/MP3", true], // Case insensitive
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[" audio/ogg ", true], // Whitespace trimmed
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// Invalid cases
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["video/mp4", false],
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["image/jpeg", false],
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["audio", false],
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["audio/", false],
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["/audio", false],
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])("isAudioMimeType", (mimeType, expected) => {
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expect(isAudioMimeType(mimeType as string)).toBe(expected);
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});
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test.each([
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...invalidInputs,
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// Valid text MIME types
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["text/plain", true],
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["text/html", true],
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["text/css", true],
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["TEXT/PLAIN", true], // Case insensitive
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[" text/css ", true], // Whitespace trimmed
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// Invalid cases
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["application/pdf", false],
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["image/jpeg", false],
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["text", false],
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["text/", false],
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["/text", false],
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])("isTextMimeType", (mimeType, expected) => {
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expect(isTextMimeType(mimeType as string)).toBe(expected);
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});
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test.each([
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...invalidInputs,
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// Valid application MIME types
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["application/pdf", true],
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["application/json", true],
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["application/xml", true],
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["APPLICATION/PDF", true], // Case insensitive
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[" application/xml ", true], // Whitespace trimmed
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// Invalid cases
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["text/plain", false],
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["image/jpeg", false],
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["application", false],
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["application/", false],
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["/application", false],
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])("isApplicationMimeType", (mimeType, expected) => {
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expect(isApplicationMimeType(mimeType as string)).toBe(expected);
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});
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});

‎src/lib/mimeType.ts‎

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import { isNullOrEmpty } from "./string";
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/**
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* Private helper function to check if a MIME type matches a main type pattern
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* @param mimeType The MIME type to check
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* @param mainType The main MIME type (e.g., "image", "video")
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* @returns true if the MIME type matches the pattern
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*/
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function isMainMimeType(mimeType: string, mainType: string): boolean {
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const normalizedMimeType = mimeType.toLowerCase().trim();
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return normalizedMimeType.startsWith(`${mainType}/`) && normalizedMimeType.length > mainType.length + 1;
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}
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/**
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* Check if the MIME type represents an image
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* @param mimeType The MIME type to check
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* @returns true if the MIME type is for an image
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*/
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export function isImageMimeType(mimeType?: string): boolean {
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if (isNullOrEmpty(mimeType)) {
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return false;
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}
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return isMainMimeType(mimeType!, "image");
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}
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/**
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* Check if the MIME type represents a PDF document
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* @param mimeType The MIME type to check
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* @returns true if the MIME type is for a PDF document
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*/
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export function isPdfMimeType(mimeType?: string): boolean {
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if (isNullOrEmpty(mimeType)) {
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return false;
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}
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const normalizedMimeType = mimeType!.toLowerCase().trim();
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return normalizedMimeType === "application/pdf";
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}
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/**
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* Check if the MIME type represents a video
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* @param mimeType The MIME type to check
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* @returns true if the MIME type is for a video
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*/
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export function isVideoMimeType(mimeType?: string): boolean {
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if (isNullOrEmpty(mimeType)) {
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return false;
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}
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return isMainMimeType(mimeType!, "video");
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}
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/**
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* Check if the MIME type represents an audio file
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* @param mimeType The MIME type to check
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* @returns true if the MIME type is for an audio file
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*/
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export function isAudioMimeType(mimeType?: string): boolean {
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if (isNullOrEmpty(mimeType)) {
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return false;
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}
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return isMainMimeType(mimeType!, "audio");
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}
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/**
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* Check if the MIME type represents a text file
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* @param mimeType The MIME type to check
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* @returns true if the MIME type is for a text file
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*/
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export function isTextMimeType(mimeType?: string): boolean {
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if (isNullOrEmpty(mimeType)) {
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return false;
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}
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return isMainMimeType(mimeType!, "text");
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}
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/**
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* Check if the MIME type represents an application file
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* @param mimeType The MIME type to check
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* @returns true if the MIME type is for an application file
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*/
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export function isApplicationMimeType(mimeType?: string): boolean {
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if (isNullOrEmpty(mimeType)) {
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return false;
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}
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return isMainMimeType(mimeType!, "application");
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}

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