JavaScript基础作业练习_1022

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    <title>Document</title>
    <script>
        /*
                                                                                                                                function func() {
                                                                                                                                    var a = 123;
                                                                                                                                    alert(a);
                                                                                                                                    return 'abc';
                                                                                                                                }
                                                                                                                                alert(func());
                                                                                                                                */
        /*
                var score = 90;
                if (score < 60) {
                    alert('不及格');
                }
                if (score >= 60 && score < 80) {
                    alert('良好');
                }
                if (score >= 80 && score < 90) {
                    alert('不错哦');
                }
                if (score >= 90 && score < 100) {
                    alert('优秀');
                }
        */
        /*
                var num = 6;
                for (i = 0; i < num; i++) {
                    alert('i=' + i);
                }

                var num = 1;
                while (num < 6) {
                    alert('num=' + num);
                    num++;
                }

                var num = 6;
                while (num > 6) {
                    alert('num=' + num);
                }
        */
        /*
        var num = 'asd';
        num = parseInt(num);
        //parseInt 转换为整型
        alert(typeof(num));
        if (isNaN(num)) {
            alert('转换失败');
        }
        if (isNumber(num)) {
            alert(num);
        }
        */
        /*
        var arr = [1, 2, 3, 5, 6];
        //不建议插入数据
        //arr[9] = 44;
        //往数组后面插入数据
        arr.push(44);
        alert('长度是' + arr.length);
        //弹出尾部元素
        var res = arr.pop();
        alert(res);
        console.log(arr);
        alert('长度是' + arr.length);
        */

        //var arr = [1, 2, 3, 5, 6];
        //在第一个位置添加一个元素
        //arr.unshift('abc');
        //删除第一个元素
        //var res = arr.shift();
        //alert(res);
        //console.log(arr);

        var arr = [1, 2, 3, 4, 5, 6];
        //从第几个元素开始删除几个元素
        //var res = arr.splice(2, 4);
        //console.log(res);
        //搜索目标元素，第几个元素开始找；返回改数据索引
        //var res = arr.indexOf(5, 0);
        //alert(res);
        //console.log(arr);

        //数组遍历
        // for (i = 0; i < arr.length; i++) {
        //     console.log(arr[i]);
        // }

        // var i = 0;
        // while (i < arr.length) {
        //     console.log(arr[i]);
        //     i++;
        // }
        function over() {
            console.log('鼠标滑过了');
        }

        function out() {
            console.log('鼠标划走了');
        }
    </script>
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