在输入框被聚焦时，在IE8中禁用F5 Ctr + F5和Ctrl + R.

Question

我希望在文本框聚焦时禁用网页刷新 我正在使用的代码是适用于其他快捷方式的代码 除了：

BTW我想通过简单的JavaScript没有JQuery和没有JavaScript来实现这一点 框架。

  document.onkeydown = keyDown  //control chars
document.onkeypress = keyDown   //any char/number

function keyDown(e) {

        //74=j, 75=k, 78=n, 84=t
        var forbiddenCtrlKeys = new Array(74,75,78, 84);
        //37=left_arrow, 39=right_arrow
        var forbiddenAltKeys = new Array(37,39);
        //8=backspace, 116=F5
        var forbiddenSingleKeys = new Array(8,116);
        //per le textbox 116=F5
        var forbiddenTextBoxKeys = new Array(116);

        key = window.event.keyCode;     //IE

              if(window.event.ctrlKey){ //ctrl
                    isCtrl = true;
                    isAlt = false

                    checkVal(forbiddenCtrlKeys,window.event.keyCode);
              }
              else if(window.event.altKey){ //alt
                    isCtrl = false;
                    isAlt = true;
                    checkVal(forbiddenAltKeys,window.event.keyCode);
              }

              else{ //other

                    isCtrl = false;
                    isAlt = false;
                    var element = e.target.nodeName.toLowerCase();
                    var curr = document.activeElement
                    if(curr.tagName=="INPUT")
                    alert(curr.tagName);

                    if((element != 'input' && element != 'textarea') || $(e.target).attr("readonly")){
                        alert(window.event.keyCode);
                        checkVal(forbiddenSingleKeys,window.event.keyCode); 
                    }
                    if(document.event.keyCode==116){
                        alert(window.event.keyCode);
                        document.event.keyCode=0;
                        checkVal(forbiddenTextBoxKeys,window.event.keyCode);
                    }       
              }
}

function checkVal(set,key){


        for(i in set)
        {
        //case-insensitive comparison
            if(String.fromCharCode(set[i]).toLowerCase() == String.fromCharCode(key).toLowerCase())
                        {
                                alert('This key combination has been disabled.');
                                window.event.returnValue =        false;    
                                window.event.keyCode = 0;
                                return true;
                        }
        }
}

所以我试图在其他情况下尝试实现的是每当我尝试按F5禁用它时 但它不起作用，任何见解都会受到高度赞赏