Using FetchXML in a CRM form without having to use string concatenation

I am a solution architect using Microsoft Dynamics CRM, and I must be the laziest programmer I know. I HATE to write FetchXML code embedded in Javascript. But I am getting over it. I started using FetchXML Builder add-on to XRM Toolbox and that was very helpful for working with CRM Online. But last week I needed to query the Product table in a custom form to pull back a list price of a product, and I was dreading the thought of having to add all the little quotes and doing string concatenation because I knew I would be tweeking it and repeatedly making changes in FetchXML builder, them moving the query code back to Javascript and making it a bunch of concatenated strings (wash, rinse, repeat).

If I were putting the FetchXML into a C# program, no problem because that language supports having multi-line strings. And I could use Format.string() to insert my parameters into the code so I don't have to concatenate that either.

Not so much in Javascript. So I did some research and found some articles on how it could be done. I can put the FetchXML between comments and then use a regular expression to make it into a legit string. As long as nobody turns on 'compression' on the web server, it should continue to work. The code looks like this:

	function fetchGetProduct() {
	try {
	// Get the price of the product requested
	var sFetch = (function () {/*
	<fetch count="1" >
	<entity name="product" >
	<attribute name="price" />
	<filter type="and">
	<condition attribute="productid" operator="eq" value="{0}" />
	</filter>
	</entity>
	</fetch>
	*/}).toString().match(/[^]*\/\*([^]*)\*\/\}$/)[1];
	// use this trick to insert the GUID into the fetch query at position {0}
	var v1 = Xrm.Page.getAttribute("new_quickaddproductid").getValue()[0].id;
	sFetch = sFetch.format(v1);
	// alert(sFetch);
	_oService = new FetchUtil(_sOrgName, _sServerUrl);
	// get the price from CRM, and use updatePrice() as the callback
	_oService.Fetch(sFetch, updatePrice);
	}
	catch (e) {
	}
	}
	function updatePrice(results) {
	// given the results of the FetchXML
	// get the list price from the product it returned
	if (results.length > 0) {
	var listprice = results[0].attributes["price"].value;
	// update the price field on the custom form
	Xrm.Page.getAttribute("new_quickaddamount").setValue(parseFloat(listprice));
	}
	}
	// this function lets me replace a positional parameter in
	// First, checks if it isn't implemented yet.
	if (!String.prototype.format) {
	String.prototype.format = function () {
	var args = arguments;
	return this.replace(/{(\d+)}/g, function (match, number) {
	return typeof args[number] != 'undefined'
	? args[number]
	: match
	;
	});
	};
	}

view raw fetchGetProduct hosted with ❤ by GitHub

The last function in this takes care of replacing the {0} in my FetchXML with the GUID I need in the query. Line 15 of my code gets the GUID from a lookup field, and Line 16 calls the Format function to replace the {0} parameter with the GUID.