TypeError: regex match is not a function in JavaScript [Fix]

# Table of Contents

1. TypeError: regex match is not a function in JavaScript
2. TypeError: regex test is not a function in JavaScript

# TypeError: regex match is not a function in JavaScript

The "TypeError: match is not a function" error occurs when the match method is called on a value that is not of type string.

To solve the error, make sure to only call the match method on strings, e.g. 'ABC'.match(/[A-Z]/g).

Here is an example of how the error occurs.

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const str = {};

// ⛔️ TypeError: match is not a function
const result = str.match(/[A-Z]/g);

We called the String.match method on an object and got the error back.

# Only call the match() method on strings

To solve the error, console.log the value you're calling the match method on and make sure to only call the method on strings.

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const str = 'Bobby Hadz';

const result = str.match(/[A-Z]/g);

console.log(result); // 👉️ ['B', 'H']

If the value is not a string, you can convert it using the String() constructor.

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const num = 1234;

// 👇️ use String() to convert to string first
const result = String(num).match(/[0-2]/g);

console.log(result); // 👉️ ['1', '2']

The String() constructor converts the supplied value to a string and returns the result.

# Check if the value is a string before calling match()

Alternatively, you can check if the value is a string before calling the match() method.

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const str = null;

const result =
  typeof str === 'string' ? str.match(/[0-2]/g) : null;

console.log(result); // 👉️ null

We used a ternary operator to check if the str variable stores a string.

If it does, the value to the left of the comma is returned, otherwise, the value to the right is returned.

You could also use an if statement to achieve the same result.

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const str = undefined;

let result = null;

if (typeof str === 'string') {
  result = str.match(/[0-2]/g);
}

console.log(result); // 👉️ null

If the error persists, console.log the value you're calling the match method on and check its type using the typeof operator.

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console.log(typeof 'bobbyhadz.com'); // 👉️ string
console.log(typeof 12345); // 👉️ number
console.log(typeof []); // 👉️ object

If the value is an object, there's a very good chance that you are forgetting to access a specific property on which you need to call the match() method.

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// ✅ with objects
const obj = {
  example: '123456',
};

const result1 = obj.example.match(/[0-2]/g);
console.log(result1); // 👉️ [ '1', '2' ]

// --------------------------------------------
// ✅ with arrays

const arr = ['123456', '45', '74'];

const result2 = arr[0].match(/[0-2]/g);
console.log(result2); // 👉️ [ '1', '2' ]

We accessed a property on the object and an element in the array before calling the String.match() method.

# TypeError: regex test is not a function in JavaScript

The "test is not a function" error occurs when the test() method is called on a value that is not a regular expression, e.g. a string.

To solve the error, make sure to only call the test method on regular expressions, e.g. /[a-b]/.test('abc').

Here is an example of how the error occurs.

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const regex = '[a-z]';

// ⛔️ TypeError test is not a function
const result = regex.test('example');

We called the RegExp.test method on a string and got the error back.

# Only call the test() method on regular expressions

To resolve the issue, make sure to only call the test() method on regular expressions.

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const result = /[a-z]/.test('example');

console.log(result); // 👉️ true

Notice that the regular expression is not wrapped in a string.

The forward slashes / / mark the beginning and end of the regex.

# Don't wrap regular expressions in quotes

When storing the regular expression in a variable, make sure to not wrap it in quotes.

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const regex = /[a-z]/;

const result = regex.test('example');

console.log(result); // 👉️ true

If the regex is wrapped in quotes, it becomes a string and strings don't implement a test() method.