type error js cannot read property code example

Example 1: cannot read property

/* This error occurs in Chrome Browser when you read a property or call 
a method on an undefined object. */
// To handle it, use "Optional Chaining" compatible with Node.js v14.0.0

Syntax -> ?.
Usage ->
let obj;
console.log(obj.a) // Cannot read property 'a' of undefined
console.log(obj?.a) // Works like a charm

Example 2: cannot read property

// That is mostly because the object was not declared until the moment when the code ran,
// Example:


console.log(object.list.map(el => el.name))

const object = {
	list: [
    	{name: 'test'},
        {name: 'second'}
    ]
}

// The error happens because the object was created after the map call
// The same happens if you forgot to import a package for example.

// If you are dealing with a situation that you don't know if the object
// has an specific property, you can use a question mark to tell the compiler
// that maybe the property doesen't exists, returning undefined:

console.log(object.default.size) // error
console.log(object.list[1]?.age) // undefined
console.log(object.default?.color) // undefined