problem in understanding the code snipet

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Javascript

I am new to javascript ,I am feeling problem in understand the code.Real problem i am facing is that what is this configuration is it a function a variable or json object ????? Any help will be greatly appreciated.

configuration = {
    on: {
        start: function (transactionid, arguments) {        
            statusElement.append("<li>YUI IO Ajax Request STARTED [transactionid = " + transactionid + " , response = no response]</li>");
            },

        success: function (transactionid, response, arguments) {        
            statusElement.append("<li>YUI IO Ajax Request SUCCESS [transactionid = " + transactionid + " , responseText = " + response.responseText + " response.status = " + response.status + "]</li>");
        },

        failure: function (transactionid, response, arguments) {        
            statusElement.append("<li>YUI IO Ajax Request FAILURE [transactionid = " + transactionid + " , responseText = " + response.responseText + " response.status = " + response.status + "]</li>");
        },

        complete: function (transactionid, response, arguments) {        
            statusElement.append("<li>YUI IO Ajax Request COMPLETED [transactionid = " + transactionid + " , responseText = " + response.responseText + "response.status = " + response.status + "]</li>");
        },

        end: function (transactionid, arguments) {        
            statusElement.append("<li>YUI IO Ajax Request END [transactionid = " + transactionid + " , response = no response]</li>");
        }
    }
    };