使用window.onload在javascript onsubmit中加载多个函数 [英] load multiple function in javascript onsubmit using window.onload

问题描述

HY！我正在使用javascript来为每个使用单独的函数验证不同的表单，现在的问题是，当我在window.onload上加载一个函数时，它将正常工作，但是当我加载多个函数时，只有第一个将工作，其余的将不？要知道什么是错误，我使用try catch，这个错误将显示

Hy! i am using javascript to validate different forms using separate function for each, now the problem is that when i load one function on window.onload the it will work fine but when i load multiple function then only the first one will work and the rest will not? to know what is the error i use try catch and this error will shown

typeerror:cannot set property 'onsubmit' of null

这是我的代码...

this is my code...

//validation of registration page..
function validate_form_registration()
{


    document.getElementById('form_reg').onsubmit=function()
    {
        if (document.getElementById('first_name').value.length=="")
        {
            document.getElementById('error').innerHTML="please enter first name";
            document.getElementById('first_name').focus();
            return false;
        }

        else if (document.getElementById('last_name').value.length=="")
        {
            document.getElementById('error').innerHTML="please enter Last name";
            document.getElementById('last_name').focus();
            return false;
        }
        else if (document.getElementById('username').value.length=="")
        {
            document.getElementById('error').innerHTML="please enter Username";
            document.getElementById('username').focus();
            return false;
        }
        else if (document.getElementById('mail').value.length=="")
        {
            document.getElementById('error').innerHTML="please enter Email";
            document.getElementById('mail').focus();
            return false;
        }
        else if (document.getElementById('dept').value.length=="")
        {
            document.getElementById('error').innerHTML="please enter your Department";
            document.getElementById('dept').focus();
            return false;
        }
        else if (document.getElementById('id_number').value.length=="")
        {
            document.getElementById('error').innerHTML="please enter ID number";
            document.getElementById('id_number').focus();
            return false;
        }
        else if (document.getElementById('phone').value.length=="")
        {
            document.getElementById('error').innerHTML="please enter Phone number";
            document.getElementById('phone').focus();
            return false;
        }
        else if (document.getElementById('address').value.length=="")
        {
            document.getElementById('error').innerHTML="please enter Your Adress";
            document.getElementById('address').focus();
            return false;
        }
        else

        {
            document.getElementById('error').innerHTML="";
            return true;
        }

    };
};
//end of registration page...

//validation of login page.....
function validate_form_login()
{
    document.getElementById('form_log').onsubmit=function()
    {
        if(document.getElementById('username').value.length=='')
        {
            document.getElementById('error').innerHTML='Please enter username';
            document.getElementById('username').focus();
            return false;
        }
        else if(document.getElementById('password').value.length=='')
        {
            document.getElementById('error').innerHTML='Please enter password';
            document.getElementById('password').focus();
            return false;
        }
        else
        {
            document.getElementById('error').innerHTML='';
            return true;
        }
    };
};
//validation of application page..

function validate_form_aplic()
{
    document.getElementById('form_anous').onsubmit=function(){
        if(document.getElementById('select_item').value.length=='')
        {
            document.getElementById('error').innerHTML='Please select leave type';
            document.getElementById('select_item').focus();
            return false;
        }
       else if(document.getElementById('txtarea').value.length=='')
        {
            document.getElementById('error').innerHTML='Please enter application';
            document.getElementById('txtarea').focus();
            return false;
        }
       else if(document.getElementById('fromt').value.length=='')
        {
            document.getElementById('error').innerHTML='Please enter time';
            document.getElementById('fromt').focus();
            return false;
        }
       else if(document.getElementById('tot').value.length=='')
        {
            document.getElementById('error').innerHTML='Please enter time limit';
            document.getElementById('tot').focus();
            return false;
        }
        else
        {
            document.getElementById('error').innerHTML='';
            return true;
        }
    };
};
window.onload=function()
{ try {
    validate_form_aplic();
    validate_form_login();
    validate_form_registration();
}
 catch (error)
 {
     alert(error);
 }
};

如何解决？为什么window.onload可以覆盖所有其他的第一个函数，s？有没有办法解决它？

how to solve it? why the window.onload can overwrite the first function on all the other,s? is there a way to solve it?

推荐答案

你没有告诉我们onsubmit三次出现的错误，但显然你需要我们调试器...

getElementById中的一个或多个返回null。使用调试器查看哪个并检查HTML页面中的相应元素...

You do not tell us on which of the three occurrences of onsubmit you got the error, but obviously you have to us debugger...
One - or more - of the getElementById returns null. Use debugger to see which and check the corresponding element in your HTML page...

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