Uncaught TypeError: Cannot read property 'value' of undefined

user_572737 0
Viewed 670951

I have some JavaScript code that gives this error

Uncaught TypeError: Cannot read property 'value' of undefined

Code

var i1 = document.getElementById('i1');
var i2 = document.getElementById('i2');
var __i = {'user' : document.getElementsByName("username")[0], 'pass' : document.getElementsByName("password")[0] };
if(  __i.user.value.length >= 1 ) { i1.value = ''; } else { i1.value = 'Acc'; }

if(  __i.pass.value.length >= 1 ) { i2.value = ''; } else { i2.value = 'Pwd'; }

What does this error mean?

typeerror javascript
7 Answers

You can just create a function to check if the variable exists, else will return a default value :

function isSet(element, defaultVal){

    if(typeof element != 'undefined'){

        return element;

    }

    console.log('one missing element');

    return defaultVal;
}

And use it in a variable check:

var variable = isSet(variable, 'Default value');
user_24026100

You code looks like automatically generated from other code - you should check that html elements with id=i1 and i2 and name=username and password exists before processing them.

user_8600990
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