[php学习十一]javaScript的基本练习2

「爱情、让人受尽委屈。」 2022-09-24 06:22 144阅读 0赞

<!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>HTML随便练习4</title>
        <style>
            p{background: center; background-color: #FFA500; text-align: center;}
        </style>
    </head>
    <script>
        function btnClick(){
            try {
                /*注意点1:throw抛异常的时候一定要NEW个异常对象,否则获取不到异常信息~~*/
                var buf = document.getElementById("IntValue").value.trim();
                var y =document.getElementById("InputResult");
                if (buf == "") throw new Error("值不能为空");
                if (isNaN(buf)) throw new Error("不是数字");
                if (buf < 0) throw new Error("不能小于0");
                if (buf > 10 ) throw Error("不能大于10");
                y.innerHTML="数字正确.";
            }
            catch (err){
                y.innerHTML="错误：" + err.message + "。";
            }
        }
    </script>
    <body>
    <input title="输入" type="text" id="IntValue" value="请输入[0..10]的数" style="color:olivedrab ; width: 200px"
           οnclick="this.value ='' ">
    <div id="InputResult" style="color: brown" ></div>
    <input type="button" οnclick="btnClick()" value="确定">
    <p><small>数组与对象使用</small></p>
    <div id="ArrAndObj"></div>
    <p><small>查找最大的数</small></p>
    <div id="findMax"></div>
    <p><small>闭包调用三次</small></p>
    <div id = "TimeCount"></div>
    <script language="javascript">
        function showObj(aobj){
            var r = "";
            for (var buf in aobj){
                /*注意点2:推荐用typeof aobj[buf] == "function"进行类型判断~~*/
                if (aobj[buf].constructor.toString().indexOf("Function") > -1){
                    r += buf + ":" + aobj[buf]() + ";";
                }
                else{
                    r += buf + ":" + aobj[buf] + ";";
                }
            }
            return r;
        }
        var arr = [];
        arr[0] = "Hello";
        arr[1] = "World";
        var  obj = [2];
        /*注意点3:一旦以哈希的方式赋值后,就不能用数组的方法了,如length,arr[0]等~*/
        obj["a"] = "Hello";
        obj["b"] = "World";
        obj["c"] = function () {return false};
        document.getElementById("ArrAndObj").innerHTML = "arr为数组:" + arr.toString() + ";长度:" + arr.length + "arr[0]=" + arr[0] + "<br>"
                +"Obj为对象:" + showObj(obj) + "长度" + obj.length + ";obj['a']或obj.a=" + obj.a;
        function findMaxNumber() {
            var max = 0;
            for (var i = 0; i < arguments.length; i ++){
                if (arguments[i] > max){
                    max = arguments[i];
                }
            }
            return max;
        }
        document.getElementById("findMax").innerHTML = "(2,3,4,5)最大数为:" + findMaxNumber(2,3,4,5);
        /*注意点4:闭包是可访问上一层函数作用域里变量的函数，即便上一层函数已经关闭。*/
        var Times = (function () {
            var time = 0;
            return function () {
               return time+=1;
            }
        })();
        document.getElementById("TimeCount").innerHTML = "第一次值:" + Times() + ";第二次值:" + Times() + ";第三次值:" + Times();
    </script>
    
    </body>
    </html>