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 query
- Cannot read property bind
- Cannot read property style
- Cannot read property scrolltop
- Cannot read property left
- Cannot read property filter
- Cannot read property document
- Cannot read property contains
- Cannot read property set
- Cannot read property classname
- Cannot read property 3
- Cannot read property indexof
- Cannot read property browser
- Cannot read property match
- Cannot read property getelementsbytagname
- Cannot read property classlist
- Cannot read property jquery
- Cannot read property history
- Cannot read property getitem
- Cannot read property firstchild
- Cannot read property validate
- Cannot read property tostring
- Cannot read property play
- Cannot read property setstate
- Cannot read property zindex
- Cannot read property focus
- Cannot read property helpers
- Cannot read property reduce
- Cannot read property getelementsbyclassname
- Cannot read property add
- Cannot read property width
- Cannot read property preventdefault
- Cannot read property split
- Cannot read property error
- Cannot read property key
- Cannot read property version
- Cannot read property option
- Cannot read property defaultview
- Cannot read property call
- Cannot read property nodename
- Cannot read property then
- Cannot read property datatable
- Cannot read property keyboard
- Cannot read property remove
- Cannot read property xlsx
- Cannot read property header
- Cannot read property webkit
- Cannot read property type
- Cannot read property editor
- Cannot read property getattribute
- Cannot read property hide
- Cannot read property toggle
- Cannot read property document
- Cannot read property x
- Cannot read property jspdf
- Cannot read property install
- Cannot read property includes