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for循環(huán),while循環(huán),do while循環(huán)是否可以互相替代呢?

Original 2019-04-15 16:06:30 1074
abstract:<!DOCTYPE html> <html>     <head>         <meta charset="utf-8">      &
<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8">
        <title></title>
        <style type="text/css">
            
        </style>
    </head>
    <body>
        <input type="checkbox" id="checkall" onclick="checkAll()"><lable for="checkall">全選</lable>
        <hr>
        <input type="checkbox" name="item[]">選項(xiàng)1<br>
        <input type="checkbox" name="item[]">選項(xiàng)2<br>
        <input type="checkbox" name="item[]">選項(xiàng)3<br>
        <input type="checkbox" name="item[]">選項(xiàng)4<br>
        <input type="checkbox" name="item[]">選項(xiàng)5<br>
        <input type="checkbox" name="item[]">選項(xiàng)6<br>
        <input type="checkbox" name="item[]">選項(xiàng)7<br>
        <input type="checkbox" name="item[]">選項(xiàng)8<br>
        <input type="checkbox" name="item[]">選項(xiàng)9<br>
        <input type="checkbox" name="item[]">選項(xiàng)10<br>
        <br>
        <p>分別使用for循環(huán),while循環(huán),do while循環(huán)做了全選的案例,都可以實(shí)現(xiàn)效果,那么這三種循環(huán)語句是否可以互相替代通用呢?</p>
        
        <script type="text/javascript">
            /* function checkAll(){
                var checkall , item;
                checkall = document.getElementById('checkall');
                item = document.getElementsByName('item[]');
                
                for(var i = 0; i<item.length; i++){
                    if(checkall.checked){
                        item[i].checked = true;
                        
                    }else{
                        item[i].checked = false;
                    }
                    
                }
            } */
            
            /* function checkAll(){
                var checkall , item;
                checkall = document.getElementById('checkall');
                item = document.getElementsByName('item[]');
                var i=0;
                while(i<=item.length){
                    if(checkall.checked){
                        item[i].checked = true;
                    }else{
                        item[i].checked = false;
                    }
                    i++;
                }
                
            } */
            
            
            
            
             function checkAll(){
                var checkall , item;
                checkall = document.getElementById('checkall');
                item = document.getElementsByName('item[]');
                var i=0;
                do{
                    if(checkall.checked){
                        item[i].checked = true;
                    }else{
                        item[i].checked = false;
                    }
                    i++
                }while(i<=item.length);
            }
            
        </script>
    </body>
</html>


Correcting teacher:查無此人Correction time:2019-04-16 09:55:27
Teacher's summary:完成的不錯(cuò)。想到問題,可以自己動(dòng)手測(cè)試下。我回答你可以,那你還是不知道怎么寫的。繼續(xù)加油。

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