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  • js禁用回退键

           function forbidBackSpace(e) {
                var ev = e || window.event; //获取event对象   
                var obj = ev.target || ev.srcElement; //获取事件源   
                var t = obj.type || obj.getAttribute('type'); //获取事件源类型   
                //获取作为判断条件的事件类型   
                var vReadOnly = obj.readOnly;
                var vDisabled = obj.disabled;
                //处理undefined值情况   
                vReadOnly = (vReadOnly == undefined) ? false : vReadOnly;
                vDisabled = (vDisabled == undefined) ? true : vDisabled;
                //当敲Backspace键时,事件源类型为密码或单行、多行文本的,   
                //并且readOnly属性为true或disabled属性为true的,则退格键失效   
                var flag1 = ev.keyCode == 8 && (t == "password" || t == "text" || t == "textarea") && (vReadOnly == true || vDisabled == true);
                //当敲Backspace键时,事件源类型非密码或单行、多行文本的,则退格键失效   
                var flag2 = ev.keyCode == 8 && t != "password" && t != "text" && t != "textarea";
                //判断   
                if (flag2 || flag1) return false;
            }
            //禁止后退键 作用于Firefox、Opera  
            document.onkeypress = forbidBackSpace;
            //禁止后退键  作用于IE、Chrome  
            document.onkeydown = forbidBackSpace; 

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  • 原文地址:https://www.cnblogs.com/xm_cpppp/p/2667267.html
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