Typeerror cannot read property push of undefined

In this article, we will explain to you the solutions in detail on how to solve the typeerror: cannot read property ‘push’ of undefined.

Also, we’ll discuss what it means, why this error occurs and provide an example to help you understand the cause of an error.

What is the “Typeerror Cannot Read Property ‘Push’ of Undefined” Error?

The “Cannot Read Property Push of Undefined” Error is a common JavaScript error that occurs if you are trying to push a value to an undefined variable.

In other words, this error occurs when you’re trying to add an item to an array which is not defined.

Here’s an example of the error message you need to see:

Uncaught TypeError: Cannot read property ‘push’ of undefined

Why Does the “Typeerror: Cannot Read Property Push of Undefined” Error Occur?

The “Typeerror: Cannot Read Property Push of Undefined” error occur because you’re trying to push a value to an array which is not initialized or defined.

In other words, the variable you are trying to push the value that does not exist or it is not properly declared.

Another reason for this error that will occur is that you are trying to push a value to an object which is not an array.

Common Possible Caused of the Error

There are four possible reasons for the “cannot read property ‘push’ of undefined” error in JavaScript:

• Calling the push() method on a variable without first initializing it with an array.
• Calling the push() method on an array element instead of the array itself.
• Calling the push() method on a variable that was previously set to undefined.
• Calling the push() method on an object property that does not exist or has a value of undefined.

Solutions to Solve the Error

Here are the following solutions to solve. The Typeerror cannot read property push of undefined.

Solution 1: Initialize or Define Your Array Variable

To solve this error, you need to make sure that the array variable has correctly initialized or defined.

Here’s an example of how to define an array variable:

const myArray = [];

In this example, we’ve defined an empty array called “myArray”. Now we can push values to this array without getting the “Cannot Read Property Push of Undefined” error.

Let’s take a look the another example:

let multipliedNums = [];
let nums = [2, 4, 6, 8, 10];
for (const num of nums) {
  let double = num * 6;

  multipliedNums.push(double);
}
console.log(multipliedNums);

Output:

[ 12, 24, 36, 48, 60 ]

Solution 2: Check Your Object Types

You need to make sure that the object you are trying to push a value to is an array.

You can check the type of an object using the “typeof” operator.

Here’s an example on how to check if an object is an array:

const myObject = [];

if (typeof myObject === "object" && myObject.constructor === Array) {
  // myObject is an array
}

In this example, we’ve used the “typeof” operator to check if “myObject” is an object and then performed some actions based on the result of the check.

Solution 3: Make Sure Your Function is Returning an Array

To solve this error, you need to make sure that your function is returning an array.

Here’s an example on how to return an array from a function:

function myFunction() {
  const myArray = ["apple", "banana", "orange"];
  return myArray;
}

const newArray = myFunction();

In this example, we’ve defined a function called “myFunction” that returns an array called “myArray”.

Then, we call this function and assign the returned array to a new variable called “newArray”.

Now we can push values to “newArray” without getting the “Typeerror: Cannot Read Property Push of Undefined” error.

Solution 5: Calling the push() Method on a Variable Without Initializing

If you are calling the push() method on a variable without first initializing it with an array, you’ll get the “cannot read property ‘push’ of undefined” error.

To solve this, make sure that you initialize the variable with an empty array before calling the push() method on it.

Here’s an example:

let doubles;
let nums_example = [1, 3, 5, 7, 9];
for (const num of nums_example ) {
let double = num * 5;
doubles.push(double);
}
console.log(doubles);

In the example above, the doubles variable is not initialized with an array, so calling the push() method on it causes the error.

To solve this, initialize the doubles variable with an empty array before calling the push() method on it, like this:

let doubles = [];
let number_example = [4, 8, 12, 16, 18];
for (const num of number_example) {
let double = num * 2;
doubles.push(double);
}
console.log(doubles);

Output:

[ 8, 16, 24, 32, 36 ]

Solution 6: Calling the push() Method on an Array Element

Another reason for the “cannot read property ‘push’ of undefined” error is calling the push() method on an array element instead of the array itself.

To solve this, make sure that you call the push() method on the actual array variable, not one of its elements.

Here’s an example:

const array = [];
array[0].push('apple');
array[0].push('banana');
array[0].push('orange');
console.log(array);

In the example above, the push() method is called on array[0], which is undefined because the array is empty.

To solve this, call the push() method on the array variable itself, like this:

const array = [];
array.push('apple');
array.push('banana');
array.push('orange');
console.log(array); 

Output:

‘apple’, ‘banana’, ‘orange’ ]

Additional Resources

The following articles are the common error which is be able to help to understand more about cannot read proprty:

• Uncaught typeerror: cannot read property ‘addeventlistener’ of null
• typeerror: cannot read property ‘0’ of undefined
• Typeerror cannot read property ‘map’ of undefined
• Typeerror: cannot read property ‘getrange’ of null
• Uncaught typeerror cannot read property of null

Conclusion

In conclusion, we discussed what the error means, why this error occurs, and also we provide an example to help you understand more about the cause of an error.

In addition, we’ve provided some solutions that you will be able to understand better. In this Typeerror cannot read property push of undefined.

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