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 zoneid
• Cannot read property option
• Cannot read property then
• Cannot read property preventdefault
• Cannot read property getitem
• Cannot read property readtext
• Cannot read property locals
• Cannot read property zindex
• Cannot read property document
• Cannot read property scrolltop
• Cannot read property constructor
• Cannot read property classlist
• Cannot read property split
• Cannot read property display
• Cannot read property keyup
• Cannot read property webkit
• Cannot read property value
• Cannot read property extend
• Cannot read property set
• Cannot read property find
• Cannot read property replace
• Cannot read property textcontent
• Cannot read property contains
• Cannot read property uid
• Cannot read property jquery
• Cannot read property firstchild
• Cannot read property data
• Cannot read property browserwindow
• Cannot read property words
• Cannot read property getelementsbytagname
• Cannot read property install
• Cannot read property push
• Cannot read property match
• Cannot read property 10
• Cannot read property setstate
• Cannot read property register
• Cannot read property add
• Cannot read property getcontext
• Cannot read property key
• Cannot read property name
• Cannot read property innerhtml
• Cannot read property x
• Cannot read property nodename
• Cannot read property element
• Cannot read property touppercase
• Cannot read property get
• Cannot read property style
• Cannot read property keycode
• Cannot read property visible
• Cannot read property tolowercase
• Cannot read property addeventlistener
• Cannot read property json
• Cannot read property location
• Cannot read property keyboard
• Cannot read property submit
• Cannot read property reduce
• Cannot read property appendchild

Uncaught TypeError: Cannot read property '' of null