read json file in the desktop using jquery

I have customized the XMP Sample panel and created new fields. Actually Im trying to update the values for fields from the json file. I tried many ways but won't work and integrated your code in the below app.js file but it doesn't work. Yes enabled the node parameter in manifest file. 

var filePath = '~/Desktop/RelayMetadata.json'
_jsonData = cep.fs.readFile(filePath)

//if (_jsonData.err == 0) {
	var _data = JSON.parse(_jsonData.data)
	alert(_data)
//}


$(document).ready(function () {

	/**
	 * Helper function that extracts all mandatory information needed to reference an XMP property 
	 * from a given HTML node and constructs a simple data object based on that.
	 */
	function getFieldInfo(elem, callback) {
		var $elem = $(elem);

		var field = {
			elem: $elem,
			property: $elem.attr('data-property'),
			namespace: $elem.attr('data-namespace'),
			value: $elem.val()
		};

		if ($elem.attr('data-namespace-ref')) {

			// if namespace-ref is present it needs to be resolved to a valid URI via XMPBridge.
			XMPBridge.toNamespaceURI($elem.attr('data-namespace-ref'), function (namespaceURI) {
				field.namespace = namespaceURI;
				callback(field);
			});

		} else {
			callback(field);
		}
	}


	/**
	 * We're registering our data binding code for execution once the XMPBridge is ready to use.
	 * This prevents us to access any property before the ExtendScript library is initialized 
	 * properly.
	 */
	XMPBridge.onInit(function (state) {

		if (!state.isError) {

			$("#main").show();

			// retrieve a descriptive name for the active target item�(e.g. active document, footage, ...)
			XMPBridge.getTargetName(function (targetName) {

				// stored in an arbitrary HTML element with id="target-name"
				$('#target-name').html(targetName);

			});

			// all html nodes having a "data-property" attribute will be considered for data binding.
			var $fields = $("[data-property]");

			$fields.each(function () {
				getFieldInfo(this, function (field) {

					XMPBridge.read(field.namespace, field.property, function (value) {

						// form fields are initialized with the property's current value ...
						if (field.elem.is('input,textarea')) {
							if(field.elem.attr('data-property') == 'hww_id_deliverable'){
								field.elem.val("XXXX");
							}
							if(field.elem.attr('data-property') == 'hww_product'){
								field.elem.val("test1");
							}
				
							//	field.elem.val(value);
							// ... for other elements we just replace the node's inner HTML.
						} else {
							field.elem.html(value);
						}

					});

				});
			});

			// if the form is being submitted, we update the metadata and write it back into the application DOM.
			$("form").submit(function () {

				// only process writeable property fields.
				$fields.filter('input,textarea').each(function () {
					getFieldInfo(this, function (field) {
						XMPBridge.write(field.namespace, field.property, field.value);
					});
				});

				// commit the changes so they're reflected by the application DOM.
				XMPBridge.commit();

			});

		} else {

			$("#message .text").html(state.statusMessage).parent().fadeIn();

		}

	});

});