JS: File upload validation

file-upload-validation.js

// Just some examples of how to do file validation with javascript
// IS NOT BULLETPROOF and should be coupled with server side validation
// But, it can help 

var file = this.fileInput.files[0];

		if ('name' in file) {
			name = file.name
		} else {
			name = file.fileName
		}
		if ('size' in file) {
			size = file.size
		} else {
			size = file.fileSize
		}

    if (!file || !file.type.match(/image.*/)) {
      this.onError("Only image files can be uploaded");
      return;
    } else if(size && size > 5242880){
      this.onError("Please choose a file of size 5MB or smaller");
      return;
    } else if(name && name){
			ext = name.substr(name.lastIndexOf('.') + 1).toLowerCase()
			if(ext != "jpg" && ext != "gif" && ext != "png" && ext != "jpeg") {
	      this.onError("Please choose an image of type 'jpeg', 'jpg', 'png', or 'gif'");
	      return;
    	}
    }