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typeerror cannot read property of undefined javascript

Mehedi Islam Ripon answered on March 26, 2023 Popularity 8/10 Helpfulness 4/10

answer typeerror cannot read property of undefined javascript

related Cannot read property of undefined

typeerror cannot read property of undefined javascript

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This error occurs when we try to access a property or a method of an object 
that is undefined or null. For example:

const person = {
name: "Kayhan",
age: 25
};
console.log(person.job.title);

The code above will throw a TypeError because person.job is undefined and we 
cannot read its title property. To fix this error, we need to check if
person.job exists before accessing its title property:

const person = {
name: "Kayhan",
age: 25
};
if (person.job) {
console.log(person.job.title);
}

To avoid this error, we should always check if an object or its property
exists before accessing it.

Popularity 8/10 Helpfulness 4/10 Language javascript

Source: Grepper

Tags: javascript typeerror undefined

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Contributed on Mar 26 2023

Mehedi Islam Ripon

0 Answers Avg Quality 2/10

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Cannot read property of undefined

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/**
 * Depending on your scenario, doing any one of the following might resolve the error:
 *
 * 1. Add an undefined check on the variable before you access it.
 * 2. Get the property/method from a replacement for the undefined variable.
 * 3. Use a fallback result instead of accessing the property.
 * 4. Check your code to find out why the variable is undefined.
 */
const auth = undefined;

console.log(auth); // undefined

// ❌ TypeError: Cannot read properties of undefined (reading 'user')
console.log(auth.user.name);



const auth = undefined;

console.log(auth); // undefined

// ✅ No error
console.log(auth?.user?.name); // undefined
            
            

const auth = undefined;

console.log(auth); // undefined

// ✅ No error
console.log(auth?.['user']?.['name']); // undefined


const arr = undefined;

console.log(arr?.[0]); // undefined

// Array containing an object
console.log(arr?.[2]?.prop); // undefined

Popularity 9/10 Helpfulness 1/10 Language javascript

Source: codingbeautydev.com

Tags: javascript j

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Contributed on Mar 27 2023

0 Answers Avg Quality 2/10

typeerror cannot read property of undefined javascript

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