Example 1 - Upload a single document

$form = new Form('plugins-file-upload-form-1', 'horizontal');

$fileUpload_config = array(
    'upload_dir'    => '../../../../../file-uploads/',
    'limit'         => 1,
    'file_max_size' => 2,
    'extensions'    => ['pdf', 'doc', 'docx', 'xls', 'xlsx', 'txt'],
    'debug'         => true
);
$form->addHelper('Allowed files: .pdf, .doc[x], .xls[x], .txt', 'single-file');
$form->addFileUpload('single-file', '', 'Attach a file', '', $fileUpload_config);

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Allowed files: .pdf, .doc[x], .xls[x], .txt
<div class="row mb-3">
	<label for="uploader-single-file" class="col-sm-4 col-form-label fileinput-label">
		Attach a file
	</label>
	<div class="col-sm-8">
		<input type="file" name="uploader-single-file" id="uploader-single-file" class="form-control" data-fileuploader-listInput="single-file">
		<span class="form-text" id="single-file-helper">Allowed files: .pdf, .doc[x], .xls[x], .txt</span>
	</div>
</div>

Example 2 - Image upload multiple with resizing, thumbnails & editor

$form = new Form('plugins-file-upload-form-2', 'horizontal');

$fileUpload_config = array(
    'xml'           => 'image-upload',
    'uploader'      => 'ajax_upload_file.php',
    'upload_dir'    => '../../../../../file-uploads/images/',
    'limit'         => 3,
    'file_max_size' => 2,
    'extensions'    => ['jpg', 'jpeg', 'png', 'gif'],
    'thumbnails'    => true,
    'editor'        => true,
    'width'         => 960,
    'height'        => 720,
    'crop'          => false
);
$form->addFileUpload('uploaded-images', '', 'Upload up to 3 images', '', $fileUpload_config);

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<div class="row mb-3">
	<label for="uploader-uploaded-images" class="col-sm-4 col-form-label fileinput-label">
		Upload up to 3 images
	</label>
	<div class="col-sm-8">
		<input type="file" name="uploader-uploaded-images" id="uploader-uploaded-images" class="form-control" data-fileuploader-listInput="uploaded-images">
	</div>
</div>