HTML and JavaScript not working correcty -

i started learning javascript , have been on html time now. know have coded right javascript code log in form.

here javascript code:

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<script> function login(){     var username=document.getelementbyid('usrnm');     var password=document.getelementbyid('pass');     if(username=="abc"){         if(password=="123"){             window.location.href="mypage.html"         }         else{             window.location.href="error.html"         }     else{         window.location.href="error.html"     } } </script> 

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and here html form:

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<form name="input" method="get"> <b>username:</b> <br> <input id="usrnm" type="text" name="usrnm"> <br> <br> <b>password:</b> <br> <input id="pass" type="password" name="pswrd"> <br> <br> <center> <input id="login" type="image" src="login.png" value="login" onclick="login()"> 

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when click on log in button. reloads same page in can see, intended call "mypage.html". i'mm starting learn javascript if there obvious reasons why code wont work, easy. =). know javascript works because when tried inserting onclick="login()" line <form name="input" method="get"> code directs me "error.html" when type on username field or password field.

you not getting element values, elements. add .value end of document.getelementbyid(id) method calls.