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Validation Demo

Extensions, MIME checks, duplicate prevention, size limits, and a custom business rule in one configuration.

What you should see: only .jpg / .png / .pdf files are accepted. Anything else is rejected client-side with a clear message before any bytes are sent.

Only JPG, PNG, and PDF files under 5 MB

Validation rules

new MultipleUpload('#demo-validation', {
    uploadUrl: '/api/upload',
    allowedExtensions: '.jpg,.png,.pdf',
    allowedMimeTypes: 'image/*,application/pdf',
    validateMimeByMagic: true,
    maxFileSize: 5 * 1024 * 1024,
    maxFiles: 5,
    preventDuplicates: true,
    customValidation: function(file) {
        if (/\s/.test(file.name)) return 'Spaces are not allowed in file names.';
    }
});