Fix the unexpected end of input error in JavaScript

If you’re getting the unexpected end of input error when trying to execute a piece of JavaScript, this blog post is for you! A number of things can cause this error, we’ll walk you through the most often mistakes that lead towards causing these errors, and how to identify and fix this error. We will also discuss the unexpected end of JSON input error as a bonus.

Unexpected end of input error

The unexpected end of input error in JavaScript can occur for a variety of reasons. One common reason is that you have an extra comma in an array or object literal, which can cause the JavaScript engine to misinterpret the code. This can be especially tricky if you’re using a minified javascript which may remove whitespace, making it difficult to spot the error.

Another possibility is that you’re missing a semicolon at the end of a statement, which can also lead to this error. Again, this can be tough to spot if you’re not used to reading minified code.

The Problem

If you’re getting an unexpected end of input error in JavaScript, it’s likely that you’re missing a } or ; somewhere in your code. Here are a few examples that can cause these errors:

const example1 = function() {
    console.log("example1");
} // ?️ missing semicolon here

const example2 = function() {
    console.log("example2");
; // ?️ missing closing curly brace

const arr = [1, 2 // ?️ missing closing square bracket

const obj = {age: 20 // ?️ missing closing curly brace
Code language: JavaScript (javascript)

The Solution

This can be especially tricky if your code is spread out over multiple lines. Make sure to check that all of your curly braces have matching opening and closing symbols and that all of your semicolons are in the right place. If you’re still having trouble, try running your code through a linter like JSLint or ESLint to catch any potential errors.

const example1 = function() {
    console.log("example1");
}; // ?️ add missing semicolon here

const example2 = function() {
    console.log("example2");
}; // ?️ add missing closing curly brace

const arr = [1, 2]; // ?️ add missing closing square bracket

const obj = {age: 20}; // ?️ add missing closing curly brace
Code language: JavaScript (javascript)

Unexpected end of JSON input error

If you have ever received unexpected end of JSON input error when trying to parse JSON data, you know how frustrating it can be. Few factors that can cause this error are:

One common cause of unexpected end of JSON input error is simply that the JSON data is not well-formed. This means that there are syntax errors in the JSON data itself.

Another common cause of this error is that the JSON data is not valid for the particular structure you are trying to parse it into. For instance, if you are trying to parse JSON data into a JavaScript object, but the JSON data contains invalid property names (such as – characters), then you will receive this error.

The Problem

const jsonData1 = JSON.stringify({
    name: "codedamn" // ?️ missing comma here
    founder: "Mehul Mohan"
});

const jsonData2 = "{"; // ?️ invalid json format

console.log(JSON.parse(jsonData1)); // ⛔️ throws an error
console.log(JSON.parse(jsonData2)); // ⛔️ throws an error
Code language: JavaScript (javascript)

The Solution

There are a few different ways that can help you detect and fix this error:

• The most common solution is to add a trailing comma to the end of the string. This will ensure that the string is properly formatted and will be parsed correctly by your code.
• You can use a tool like jsonlint to validate your JSON data. If you see any syntax errors, simply fix them and try parsing the data again.
• Make sure that your JSON data is valid for the structure you are trying to parse it into.

Finally, if none of the above solutions work, then the most likely cause of the error is that your JSON data is too large for the particular parser you are using. For instance, if you are using the express JSON parser in Node.js, it has a limit of 100kb for the size of the JSON data it can parse. If your JSON data is larger than this, you will need to use a different parser.

Hopefully, one of the above solutions will help you fix the unexpected end of JSON input error in your own code.

const jsonData1 = JSON.stringify({
    name: "codedamn", // ?️ add missing comma here
    founder: "Mehul Mohan"
});

const jsonData2 = {hello: "world"}; // ?️ valid json format

console.log(JSON.parse(jsonData1));
console.log(JSON.parse(jsonData2));
Code language: JavaScript (javascript)

Conclusion

In conclusion, If you’re seeing the unexpected end of input error in your JavaScript code, it’s likely that you’re missing a closing brace somewhere. To fix this, simply check your code for any open braces and make sure that they all have corresponding closing braces. Once you’ve done this, the error should be fixed and your code should run without issue. We also discussed the unexpected end of JSON input error as a bonus in this blog post.

Thanks for reading! I hope you end up solving the issue and carry forward with your coding. If you have any questions or comments, please feel free to contact me.

Happy coding! 🙂