Methods

In JavaScript methods are object properties containing a function definition. Within the function definition, this can be used to refer to the containing object as long as the function is defined within the object.

Note: If a function is assigned to a property later, any reference to this will reflect the context of the new function. Also, if the object’s function is assigned to a variable and executed via the variable, this will reflect the variable’s execution context.

Syntax

A method of an object is called via the following syntax:

objectName.methodName();

If a method is called without parenthesis, it is being called as a property, which means it will return the function definition, not execute the method.

Example

const car = {
make: 'Honda',
model: 'Civic',
year: 2019,
printOut: function () {
console.log(this.year + ' ' + this.make + ' ' + this.model);
},
};
car.printOut();
// Output: 2019 Honda Civic
// Referenced as a property
var method = car.printOut;
car.year = 2020;
method();
// Output: undefined undefined undefined;
// 'this' is being referenced outside an object context
// can be fixed by explicitly setting the object context with 'bind()'
method = car.printOut.bind(car);
method();
// Output: 2020 Honda Civic
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