Passing Inputparameters to Actions in MSCRM using WebAPI

Actions Input parameters:Inpuparams, Inputparameters1 are single line Text Parameters in MSCRM

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function ActionsDemos() {

    debugger;

    var data = {

        "InputParams": "Welcome to Actons Practice",

        "Inputparams1": "SUCCessful Parameters Passed"

    };

    customaction(data);

}

function customaction( dt) {

    debugger;

    var Id = Xrm.Page.data.entity.getId().substring(1, 37);

    var serverURL = Xrm.Page.context.getClientUrl();

    var req = new XMLHttpRequest();

    req.open("POST", serverURL + "/api/data/v8.0/accounts(" + Id + ")/Microsoft.Dynamics.CRM.new_SampleActions", true);

    req.setRequestHeader("Accept", "application/json");

    req.setRequestHeader("Content-Type", "application/json; charset=utf-8");

    req.setRequestHeader("OData-MaxVersion", "4.0");

    req.setRequestHeader("OData-Version", "4.0");

    req.onreadystatechange = function () {

        if (this.readyState == 4 /* complete */) {

            req.onreadystatechange = null;

            if (this.status == 200) {

                debugger;

                var data = JSON.parse(this.response);

            //    if (data['Inputparams1'] != null)  //output parameters

              //      alert(data['Inputparams1']);

            } else {

                debugger;

                //var error = JSON.parse(this.response).error; // error out Mssages

                //alert(error.message);

            }

        }

    };

    req.send(window.JSON.stringify(dt));

}