NaN when filling out the form

Question

I wanted to hide the confirmation of the password and automatically fill it in from the main text field. Here is the code:

<input type="text" size="30" name="password" id="password" value="" onkeyup="document.forms.registr.confirm_password.value=+this.value;" /> <input type="text" class="text" size="30" name="confirm_password" id="confirm_password" value="" />

As a result, when typing the characters a..z in the password field, it appears in confirm_password - NaN, and when entering numbers, everything is fine. I read in the internet about NaN, but I don’t understand why in my case it arises, I’m just copying the value of one field to another. Tell me please?!

Accepted Answer · 2011-05-05T13:41:19

It's all about the line
document.forms.registr.confirm_password.value=+this.value
For numbers + this.value is equal to this.value, and strings are reduced to numbers - it turns out to be NaN. Swap + and = or just remove +.

Answer 2 · 2011-05-05T13:42:58

Already answered to me :) "document.forms.registr.confirm_password.value = + this.value;" <- plus before this.value and conceived?

Use jquery or at least functions, do not directly ... in the code.

Maybe better this way:

  <script> function do_something(_this) { document.forms.registr.confirm_password.value=_this.value; } // или jquery $(document).ready(function() { $("#password").keyup(function() { $("#confirm_password").val($("#password").val()); }); }); </script> <input type="text" size="30" name="password" id="password" value="" onkeyup="do_something(this);" /> <input type="text" class="text" size="30" name="confirm_password" id="confirm_password" value="" />

Oh, did not immediately notice why the underscore before _this ???

NaN when filling out the form

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