NAV client control with a simple multiline text box

textbox-clientaddin.js

/**
 * NAV client control with a simple multiline text box
 * Exposes the following methods:
 *  GetText() : string
 *  SetText(string)
 *  GetReadOnly() : boolean
 *  SetReadOnly(boolean)
 * 
 * And the following events:
 *  Blur
 *  AddInReady
 */

"use strict";

var NAV = window.Microsoft.Dynamics.NAV,
    textControl = document.createElement("textarea");
    
function GetText() {
    return textControl.value;
}

function SetText(textValue) {
    textControl.value = textValue;
}

function GetReadOnly() {
    return textControl.readOnly;
}

function SetReadOnly(readOnlyValue) {
    textControl.readOnly = readOnlyValue;
}

// private functions 

function _addEvent(element,evName,fn) {
    if (element.addEventListener) {
        element.addEventListener(evName,fn,false);
    } else if (element.attachEvent) {
        element.attachEvent('on'+evName,function(e) {
            fn(e || window.event);
        });
    }
}

function _initializeControl(clientControlId) {
    var container = document.getElementById(clientControlId);
    if (!container) {
        alert("Fatal: Container not found");
        return;
    }
    textControl.style = "width: 100%; height: 100%;"
    container.appendChild(textControl);
    _addEvent(textControl, "blur", function () {
        NAV.InvokeExtensibilityMethod("Blur", null);
    });
    NAV.InvokeExtensibilityMethod("AddInReady", null);
}

// Go!
_initializeControl("controlAddIn");