Uncaught TypeError: Cannot read property '' of undefined
JavaScript Error: Uncaught TypeError: Cannot read property '' of null
JavaScript TypeError is returned when an operand or argument passed to a function is incompatible with the type expected by that operator or function. This error occurs in the browser when you read a property or call a method on an undefined object.
There are a few variations of this error depending on the property you are trying to access. Sometimes instead of undefined it will output null:
Uncaught TypeError: Cannot read property '' of null
Cannot read property '' of undefined
Cannot read property '' of null
Simply put, undefined means that a variable has been declared but has not yet been given a value. This particular error is probably the easiest to understand from an undefined point of view, because undefined is not considered an object type at all (but its own undefined type instead), and properties cannot belong to only to objects in JavaScript.
This error occurs when we want to access a property on a variable whose value is undefined or null. This error occurs when you try to call a method or try to access a property of a variable that does not exist (is not an object).
Null vs. Undefined in JavaScript The value "undefined" indicates that a variable has been declared, but no value has been assigned. On the other hand, "null" refers to a non-existent object, which basically means "empty" or "nothing". These are two values generally used to indicate the absence of something. Also, undefined and null are two distinct types: undefined is a type itself (undefined) while null is an object.
Other Javascript errors :
- Cannot read property quesryselectorall
- Cannot read property emit
- Cannot read property filter
- Cannot read property use
- Cannot read property ajax
- Cannot read property add
- Cannot read property xe
- Cannot read property x
- Cannot read property locals
- Cannot read property dataset
- Cannot read property webkit
- Cannot read property form
- Cannot read property reduce
- Cannot read property document
- Cannot read property split
- Cannot read property files
- Cannot read property replace
- Cannot read property includes
- Cannot read property innertext
- Cannot read property split
- Cannot read property view
- Cannot read property touppercase
- Cannot read property keyboard
- Cannot read property jquery
- Cannot read property render
- Cannot read property adatasort
- Cannot read property pending
- Cannot read property getattribute
- Cannot read property slice
- Cannot read property removechild
- Cannot read property register
- Cannot read property textcontent
- Cannot read property bridge
- Cannot read property addmethod
- Cannot read property contains
- Cannot read property helpers
- Cannot read property getelementsbyclassname
- Cannot read property setattribute
- Cannot read property push
- Cannot read property json
- Cannot read property write
- Cannot read property add
- Cannot read property tolowercase
- Cannot read property addeventlistener
- Cannot read property queryselector
- Cannot read property zindex
- Cannot read property remove
- Cannot read property name
- Cannot read property foreach
- Cannot read property query
- Cannot read property getelementsbytagname
- Cannot read property ext
- Cannot read property length
- Cannot read property defaultview
- Cannot read property words
- Cannot read property keycode
- Cannot read property browser