注入JS代码：

    cefApp.SetOnWebKitInitialized(func() {
        var myparamValue string
        v8Handler := cef.V8HandlerRef.New()
        v8Handler.Execute(func(name string, object *cef.ICefV8Value, arguments *cef.TCefV8ValueArray, 
        retVal *cef.ResultV8Value, exception *cef.ResultString) bool {
            fmt.Println("v8Handler.Execute", name)
            var result bool
            if name == "GetMyParam" {
                result = true
                retVal.SetResult(cef.V8ValueRef.NewString(myparamValue))
            } else if name == "SetMyParam" {
                if arguments.Size() > 0 {
                    newValue := arguments.Get(0)
                    fmt.Println("value is string:", newValue.IsString())
                    fmt.Println("value:", newValue.GetStringValue())
                    myparamValue = newValue.GetStringValue()
                    newValue.Free()
                }
                result = true
            }
            return result
        })
        //注册js
        var jsCode = `
            let test;
            if (!test) {
                test = {};
            }
            (function () {
                test.__defineGetter__('myparam', function () {
                    native function GetMyParam();
                    return GetMyParam();
                });
                test.__defineSetter__('myparam', function (b) {
                    native function SetMyParam();
                    if (b) SetMyParam(b);
                });
            })();
`
        // 注册JS 和v8处理器
        cef.RegisterExtension("v8/test", jsCode, v8Handler)
    })

JS里可以这样使用：

    <script type="application/javascript">
        function SetMyParam() {
            test.myparam = document.getElementById("newvalue").value;
        }

        function GetMyParam() {
            msg("GetMyParam", test.myparam);
        }
    </script>
 
 
<input id="newvalue" value="new value"/>
<button onclick="SetMyParam()">Set myparam value</button>
<button onclick="GetMyParam()">Get myparam value</button>
<p id="msgHtml"></p>