Tips on fixing the “Cannot Read Property “toString” of Undefined” problem

JavaScript is considered as an influential programming language in the computer. It is the most regularly used as a part of a network, whose application allows client-side scripts to interact with the user and make energetic pages.  JavaScript is  a programming language with object-oriented capabilities that is explained for that subject . The advantages of JavaScript can be named such as less server interaction; immediate feedback to the visitors; increased interactivity; and richer interfaces. However, it still has limitations. “Cannot Read Property “toString” of Undefined” is an example of the common issue in JavaScript. Today, we will suggest a quick answer for this problem and we are confident you are able to fix this error well. 

When does the “Cannot Read Property “toString” of Undefined” problem occur?

While you are trying to take a numbers’ array to store different meanings in a key, then convert them to strings. There are 5 numbers  and you want to change the array so it is an error “Cannot Read Property “toString” of Undefined “ . This is the command is being explained:

var index1 = [0, 4, 6, 2, 11]

// merge indexes into one number - to be stored in db - take apart when called
function storeVal() {
  let valueArray = []
  for(i = 0; i <= index1.length; i++) {
    let num = index1[i].toString()
    if  (num.length < 2) {
      let newString = '0' + num
    } else {
  return valueArray

Although you modify the index1 line, it does not give you the correct value. The problem is shown that you are working on a loop that does not fit with your part.

The solution for this issue 

To solve this problem, you need to change the part of the loop because it just makes sure that the array’s size is appropriate with the subject. 

for(i = 0; i <= index1.length; i++) {


for(i = 0; i < index1.length; i++) {


We hope you found the effective method to fix the issue Cannot Read Property “toString” of Undefined. If you have any further questions or concerns about this topic, please send us a comment. We are pleased when one of our posts provides useful information on this subject. Thank you for reading and see you in the next post.

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