Tips for simulating the 'this' keyword within Jest test scenarios

Within my JS script, there is a similar structure:

 window.custom_object = {
       //custom function defined
       myFunction: function(param1,param2){
    
       }
   
       myNewFunction : function(){
      
          //attempting to call myFunction from anotherFunction using 'this' keyword
          this.myFunction();
       }

    }

Even though I am trying to call myFunction in anotherFunction using the this keyword, it seems that during test executions, this does not have a reference to myFunction.

Various attempts to simulate the functionality of the this keyword or redefine it have not been successful.

javascriptjestjs

Answer №1

In order for this to reference object_name within the function testFunction_2, you can invoke it in one of the following ways:

// accessing the property directly assigns `this` to the object before the dot
object_name.testFunction_2()

const { testFunction_2 } = object_name
// if there is no property access, `this` defaults to globalThis (window object)
testFunction_2() // throws error 'this.testFunction is not a function'

// using call or apply methods
testFunction_2.call(object_name)
testFunction_2.apply(object_name)

// binding `this`
const testFnBound = testFunction_2.bind(object_name)
testFnBound()

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