[SalesForce] replaceAll() \r\n in a JSON serialized string

I can't get replaceAll to work on the '\r\n' sequence in a JSON serialized string.

I am serializing a Map object that contains long textarea fields with newlines. I need to change '\r\n' to '\\r\\n' for Javascript purposes. When I serialize the object, I see '\r\n' in the resulting string. However, none of the replaceAll lines that I try will work:

Map<Id, Job_Posting__c> jobMap = new Map<Id, Job_Posting__c>();
// job map gets populated.
String x = JSON.serialize(jobMap);
String y = x.replaceAll('\r\n', '\\r\\n');
String z = x.replaceAll('\\r\\n', '\\\\r\\\\n');

Is there something about JSON serialized strings that force a different approach? I see that the serialized string is between double quotes – does that make a difference?

Details: I want to pass a serialized map of job posting records to a Javascript function in a Visualforce page. The Javascript JSON.parse() fails with "unexpected token" when it hits the '\r\n'. If I manually edit the JSON string to be '\\r\\n' then the parse works.

Here's the Javascript on the VF page:

<script>
    // Define the CCx.pageJobSelection module - can be moved to static resource
    (function (module, $) {
        "use strict";
        var data_jobPostings;

        // intercept the 'submit' action of the HTML form 
        jQuery(document).ready( function ($) {
            //processing here.
        });

        module.initialize = function (options) {
            data_jobPostings = JSON.parse(options.jobPostings);
        };

    })(CCx.pageJobSelection = CCx.pageJobSelection || {}, jQuery);

    // initialize the module
    CCx.pageJobSelection.initialize({
        jobPostings: '{!jobMapJSON}'
    })

</script>

Here's the VF controller:

public with sharing class HL_CCx_JobSelectionController {
    public String jobMapJSON { get; private set; }
    public List<Job_Posting__c> jobs { get; private set; }
    private Map<Id, Job_Posting__c> jobMap = new Map<Id, Job_Posting__c>();

    // Constructor
    public HL_CCx_JobSelectionController() {
        jobs = CCx_JobSelector.selectActiveJobs();
        if (jobs == null) {
            ApexPages.addMessage(new ApexPages.Message(ApexPages.Severity.FATAL, 'No jobs postings available.'));
            return;
        }

        jobMap.putAll(jobs);

        // Serialize
        jobMapJSON = JSON.serialize(jobMap);
        jobMapJSON = jobMapJSON.replaceAll('\r\n', '\\r\\n');
    }
}