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this keyword

const obj = {
name: "Gautam",
// Arrow function (lexical scoping, this refers to the enclosing context)
arrow: () => {
console.log("Arrow Function:", this);
},
// Regular function expression (this refers to the calling object)
nonArrow: function () {
console.log("Regular Function:", this);
},
// Method shorthand (this refers to the calling object)
namedFunction() {
console.log("Method Shorthand:", this);
},
// Function declaration (this refers to the global object or undefined in strict mode)
functionDeclaration: function namedFunctionDeclaration() {
console.log("Function Declaration:", this);
},
// Using bind to explicitly set the value of this
bindMethod: function () {
function boundFunction() {
console.log("Bind Method:", this);
}
const boundFunctionWithThis = boundFunction.bind(this);
boundFunctionWithThis();
},
// window will get printed
nonBindMethod: function () {
function nFunction() {
console.log("Non Bind Method:", this);
}
nFunction();
},
//obj will get printed
nonBindMethodArrow: function () {
const nFunction = () => {
console.log("Non Bind Arrow Method:", this);
};
nFunction();
},
// Using call to invoke a function with a specific this value
callMethod: function () {
function calledFunction() {
console.log("Call Method:", this);
}
calledFunction.call(this);
},
// Using apply to invoke a function with a specific this value and arguments provided as an array
applyMethod: function () {
function appliedFunction() {
console.log("Apply Method:", this);
}
appliedFunction.apply(this);
},
// Callback function (this depends on how the function is invoked)
callbackExample: function (callback) {
console.log("Callback Example:", this);
callback();
},
};
obj.arrow(); // Outputs: Arrow Function: [object global] (or undefined in strict mode)
obj.nonArrow(); // Outputs: Regular Function: { name: 'Gautam', ... }
obj.namedFunction(); // Outputs: Method Shorthand: { name: 'Gautam', ... }
obj.functionDeclaration(); // Outputs: Function Declaration: [object global] (or undefined in strict mode)
obj.bindMethod(); // Outputs: Bind Method: { name: 'Gautam', ... }
obj.callMethod(); // Outputs: Call Method: { name: 'Gautam', ... }
obj.applyMethod(); // Outputs: Apply Method: { name: 'Gautam', ... }
// Using the callbackExample method with different callback functions
obj.callbackExample(() => {
//Obj will print first
console.log("Inside Arrow Callback:", this); //Window
});
obj.callbackExample(function () {
//Obj will print first
console.log("Inside Regular Callback:", this); //Window
});
obj.callbackExample(obj.namedFunction.bind(obj)); //Obj first and sec
obj.nonBindMethod(); //window
obj.nonBindMethodArrow(); //obj