Pfthb

Suppose I have a watcher that is watching an array mylist

watch 
 mylist:function()
 //Code
 

How can I programatically trigger an update on the variable and run the code (if the variable is unchanged)? How can I trigger an update if the watched variable is a nested object/array or a simple string?

Since you didn't provide any description regarding the actual use-case, the best you can probably do is to extract a method that is called in call this method manually.

data: function() 
 return myList: 
,

watch: 
 myList: this.handleListChange
,

methods: 
 handleListChange: function(a, b) 
 // .. do whatever you want to do in the watch method
 

To trigger the "watch" method you can now simply call your handleListChange method manually.

There are 2 questions:

How can I programatically trigger an update on the variable and run the code if the variable is unchanged?

You can hack it this way:

this._watchers.find(w => w.expression === "mylist").cb(this.mylist);

However, it's not part of the official Vue API. The _watchers list is rather an implementation detail. It may change in the future without any notice.

How can I trigger an update if the watched variable is a nested object/array?

Use a deep watcher:

watch: 
 mylist: 
 handler: function(val) 
 // Code
 ,
 deep: true
 

Working example: https://jsfiddle.net/LukaszWiktor/zjagahq2/

Here is how i did it

Frank was on to something, i just couldn't access the "this" context like suggested

so all had to do was pass all the args to the method.

watch: 
 myList: (...args) this.handleListChange(...args) ,