Object.observe

Object.observe(object, function) Object.unobserve(object)

Description

Object.observe calls function whenever there is a change to object. Object can be an array, collection, object, class or control. This can be very useful in debugging, to watch the value of an object change during runtime. Object.unobserve stops calling function.

Example (Basic)

Rem Object.observe Example
myArray = []
Object.observe(myArray, somethingChanged)
myArray[0]=100
myArray[0]=200

Function somethingChanged(changes)
  ForEach(changes, whatChanged)
End Function
  
Function whatChanged(chnge)
  console.log(chnge.type, chnge.name, chnge.oldValue)
End Function 

Example (JavaScript)

// Object.observe Example

myArray = [];
Object.observe(myArray, somethingChanged);
myArray[0]=100;
myArray[0]=200;

function somethingChanged(changes){
  ForEach(changes, whatChanged)
}
  
function whatChanged(chnge) {
  console.log(chnge.type, chnge.name, chnge.oldValue))
}

Output

add 0 undefined
update length 0
update 0 100 

Related Items

Do...Loop, Exit, For...Next, While...Wend, For Each...Next