Which method returns true if a string contains only alphabetical letters?

To check if a string contains only letters and numbers in JavaScript, call the test() method on this regex: /^[A-Za-z0-9]*$/. If the string contains only letters and numbers, this method returns true. Otherwise, it returns false.

function onlyLettersAndNumbers(str) {
	return /^[A-Za-z0-9]*$/.test(str);
}
const str1 = 'number60';
const str2 = 'contains spaces';
const str3 = 'has special characters !@#$%^&';
console.log(onlyLettersAndNumbers(str1)); // true
console.log(onlyLettersAndNumbers(str2)); // false
console.log(onlyLettersAndNumbers(str3)); // false

The

function onlyLettersAndNumbers(str) {
  return Boolean(str.match(/^[A-Za-z0-9]*$/));
}
const str1 = 'number60';
const str2 = 'contains spaces';
const str3 = 'has special characters !@#$%^&';
console.log(onlyLettersAndNumbers(str1)); // true
console.log(onlyLettersAndNumbers(str2)); // false
console.log(onlyLettersAndNumbers(str3)); // false

0 method searches for a match between the regular expression and a specified string.

The

function onlyLettersAndNumbers(str) {
  return Boolean(str.match(/^[A-Za-z0-9]*$/));
}
const str1 = 'number60';
const str2 = 'contains spaces';
const str3 = 'has special characters !@#$%^&';
console.log(onlyLettersAndNumbers(str1)); // true
console.log(onlyLettersAndNumbers(str2)); // false
console.log(onlyLettersAndNumbers(str3)); // false

1 and

function onlyLettersAndNumbers(str) {
  return Boolean(str.match(/^[A-Za-z0-9]*$/));
}
const str1 = 'number60';
const str2 = 'contains spaces';
const str3 = 'has special characters !@#$%^&';
console.log(onlyLettersAndNumbers(str1)); // true
console.log(onlyLettersAndNumbers(str2)); // false
console.log(onlyLettersAndNumbers(str3)); // false

1 characters are used to start and end the regular expression.

The

function onlyLettersAndNumbers(str) {
  return Boolean(str.match(/^[A-Za-z0-9]*$/));
}
const str1 = 'number60';
const str2 = 'contains spaces';
const str3 = 'has special characters !@#$%^&';
console.log(onlyLettersAndNumbers(str1)); // true
console.log(onlyLettersAndNumbers(str2)); // false
console.log(onlyLettersAndNumbers(str3)); // false

3 character matches the beginning of the string, while the

function onlyLettersAndNumbers(str) {
  return Boolean(str.match(/^[A-Za-z0-9]*$/));
}
const str1 = 'number60';
const str2 = 'contains spaces';
const str3 = 'has special characters !@#$%^&';
console.log(onlyLettersAndNumbers(str1)); // true
console.log(onlyLettersAndNumbers(str2)); // false
console.log(onlyLettersAndNumbers(str3)); // false

4 character matches the end of the string.

The square brackets (

function onlyLettersAndNumbers(str) {
  return Boolean(str.match(/^[A-Za-z0-9]*$/));
}
const str1 = 'number60';
const str2 = 'contains spaces';
const str3 = 'has special characters !@#$%^&';
console.log(onlyLettersAndNumbers(str1)); // true
console.log(onlyLettersAndNumbers(str2)); // false
console.log(onlyLettersAndNumbers(str3)); // false

5) are used to match any one of multiple specified patterns. In our example, we specify three patterns:

function onlyLettersAndNumbers(str) {
  return Boolean(str.match(/^[A-Za-z0-9]*$/));
}
const str1 = 'number60';
const str2 = 'contains spaces';
const str3 = 'has special characters !@#$%^&';
console.log(onlyLettersAndNumbers(str1)); // true
console.log(onlyLettersAndNumbers(str2)); // false
console.log(onlyLettersAndNumbers(str3)); // false

6,

function onlyLettersAndNumbers(str) {
  return Boolean(str.match(/^[A-Za-z0-9]*$/));
}
const str1 = 'number60';
const str2 = 'contains spaces';
const str3 = 'has special characters !@#$%^&';
console.log(onlyLettersAndNumbers(str1)); // true
console.log(onlyLettersAndNumbers(str2)); // false
console.log(onlyLettersAndNumbers(str3)); // false

7, and

function onlyLettersAndNumbers(str) {
  return Boolean(str.match(/^[A-Za-z0-9]*$/));
}
const str1 = 'number60';
const str2 = 'contains spaces';
const str3 = 'has special characters !@#$%^&';
console.log(onlyLettersAndNumbers(str1)); // true
console.log(onlyLettersAndNumbers(str2)); // false
console.log(onlyLettersAndNumbers(str3)); // false

8.

function onlyLettersAndNumbers(str) {
  return Boolean(str.match(/^[A-Za-z0-9]*$/));
}
const str1 = 'number60';
const str2 = 'contains spaces';
const str3 = 'has special characters !@#$%^&';
console.log(onlyLettersAndNumbers(str1)); // true
console.log(onlyLettersAndNumbers(str2)); // false
console.log(onlyLettersAndNumbers(str3)); // false

6 matches any uppercase letter.

function onlyLettersAndNumbers(str) {
  return Boolean(str.match(/^[A-Za-z0-9]*$/));
}
const str1 = 'number60';
const str2 = 'contains spaces';
const str3 = 'has special characters !@#$%^&';
console.log(onlyLettersAndNumbers(str1)); // true
console.log(onlyLettersAndNumbers(str2)); // false
console.log(onlyLettersAndNumbers(str3)); // false

7 matches any lowercase letter.

function onlyLettersAndNumbers(str) {
  return Boolean(str.match(/^[A-Za-z0-9]*$/));
}
const str1 = 'number60';
const str2 = 'contains spaces';
const str3 = 'has special characters !@#$%^&';
console.log(onlyLettersAndNumbers(str1)); // true
console.log(onlyLettersAndNumbers(str2)); // false
console.log(onlyLettersAndNumbers(str3)); // false

8 matches any digit.

The

const str1 = 'number60';
const str2 = 'contains spaces';
const str3 = 'has special characters !@#$%^&';
// [ 'number60', index: 0, input: 'number60', groups: undefined ]
console.log(str1.match(/^[A-Za-z0-9]*$/));
console.log(str2.match(/^[A-Za-z0-9]*$/)); // null
console.log(str3.match(/^[A-Za-z0-9]*$/)); // null

2 character matches zero or more occurrences of a particular pattern. We add it after the square brackets to match any of the patterns in the brackets as many times as possible.

2. The String match() Method

We can use the

const str1 = 'number60';
const str2 = 'contains spaces';
const str3 = 'has special characters !@#$%^&';
// [ 'number60', index: 0, input: 'number60', groups: undefined ]
console.log(str1.match(/^[A-Za-z0-9]*$/));
console.log(str2.match(/^[A-Za-z0-9]*$/)); // null
console.log(str3.match(/^[A-Za-z0-9]*$/)); // null

3 method in place of

const str1 = 'number60';
const str2 = 'contains spaces';
const str3 = 'has special characters !@#$%^&';
// [ 'number60', index: 0, input: 'number60', groups: undefined ]
console.log(str1.match(/^[A-Za-z0-9]*$/));
console.log(str2.match(/^[A-Za-z0-9]*$/)); // null
console.log(str3.match(/^[A-Za-z0-9]*$/)); // null

4 test().

function onlyLettersAndNumbers(str) {
  return Boolean(str.match(/^[A-Za-z0-9]*$/));
}
const str1 = 'number60';
const str2 = 'contains spaces';
const str3 = 'has special characters !@#$%^&';
console.log(onlyLettersAndNumbers(str1)); // true
console.log(onlyLettersAndNumbers(str2)); // false
console.log(onlyLettersAndNumbers(str3)); // false

The

const str1 = 'number60';
const str2 = 'contains spaces';
const str3 = 'has special characters !@#$%^&';
// [ 'number60', index: 0, input: 'number60', groups: undefined ]
console.log(str1.match(/^[A-Za-z0-9]*$/));
console.log(str2.match(/^[A-Za-z0-9]*$/)); // null
console.log(str3.match(/^[A-Za-z0-9]*$/)); // null

3 method returns an array of all the matches of a regular expression in a string. If there are no matches, it returns

const str1 = 'number60';
const str2 = 'contains spaces';
const str3 = 'has special characters !@#$%^&';
// [ 'number60', index: 0, input: 'number60', groups: undefined ]
console.log(str1.match(/^[A-Za-z0-9]*$/));
console.log(str2.match(/^[A-Za-z0-9]*$/)); // null
console.log(str3.match(/^[A-Za-z0-9]*$/)); // null

6.

const str1 = 'number60';
const str2 = 'contains spaces';
const str3 = 'has special characters !@#$%^&';
// [ 'number60', index: 0, input: 'number60', groups: undefined ]
console.log(str1.match(/^[A-Za-z0-9]*$/));
console.log(str2.match(/^[A-Za-z0-9]*$/)); // null
console.log(str3.match(/^[A-Za-z0-9]*$/)); // null

We pass the result of match() to the Boolean constructor to convert it to a

const str1 = 'number60';
const str2 = 'contains spaces';
const str3 = 'has special characters !@#$%^&';
// [ 'number60', index: 0, input: 'number60', groups: undefined ]
console.log(str1.match(/^[A-Za-z0-9]*$/));
console.log(str2.match(/^[A-Za-z0-9]*$/)); // null
console.log(str3.match(/^[A-Za-z0-9]*$/)); // null

7.

const str1 = 'number60';
const str2 = 'contains spaces';
const str3 = 'has special characters !@#$%^&';
// [ 'number60', index: 0, input: 'number60', groups: undefined ]
console.log(str1.match(/^[A-Za-z0-9]*$/));
console.log(str2.match(/^[A-Za-z0-9]*$/)); // null
console.log(str3.match(/^[A-Za-z0-9]*$/)); // null

8 converts truthy values to true, and falsy values to false.

In JavaScript, there are six falsy values:

console.log(Boolean(undefined)); // false
console.log(Boolean(['number60'])); // true
console.log(Boolean(null)); // false
console.log(Boolean(5)); // true

1,

const str1 = 'number60';
const str2 = 'contains spaces';
const str3 = 'has special characters !@#$%^&';
// [ 'number60', index: 0, input: 'number60', groups: undefined ]
console.log(str1.match(/^[A-Za-z0-9]*$/));
console.log(str2.match(/^[A-Za-z0-9]*$/)); // null
console.log(str3.match(/^[A-Za-z0-9]*$/)); // null

6,

console.log(Boolean(undefined)); // false
console.log(Boolean(['number60'])); // true
console.log(Boolean(null)); // false
console.log(Boolean(5)); // true

3,

console.log(Boolean(undefined)); // false
console.log(Boolean(['number60'])); // true
console.log(Boolean(null)); // false
console.log(Boolean(5)); // true

4,

console.log(Boolean(undefined)); // false
console.log(Boolean(['number60'])); // true
console.log(Boolean(null)); // false
console.log(Boolean(5)); // true

5 (empty string), and false. Every other value is truthy.

console.log(Boolean(undefined)); // false
console.log(Boolean(['number60'])); // true
console.log(Boolean(null)); // false
console.log(Boolean(5)); // true

Removing Letters and Numbers from a String

If you would like to remove any letters and numbers from the string, you can use the

console.log(Boolean(undefined)); // false
console.log(Boolean(['number60'])); // true
console.log(Boolean(null)); // false
console.log(Boolean(5)); // true

7 method.

function removeLettersAndNumbers(str) {
  return str.replace(/[A-Za-z0-9]/g, '');
}
const str1 = 'number!60 ?';
const str2 = '#wel_com%e';
console.log(removeLettersAndNumbers(str1)); // ! ?
console.log(removeLettersAndNumbers(str2)); // #_%

The

console.log(Boolean(undefined)); // false
console.log(Boolean(['number60'])); // true
console.log(Boolean(null)); // false
console.log(Boolean(5)); // true

7 method returns a new string with some or all matches of a specified pattern replaced by a replacement. We use an empty string (

console.log(Boolean(undefined)); // false
console.log(Boolean(['number60'])); // true
console.log(Boolean(null)); // false
console.log(Boolean(5)); // true

5) as the replacement to have all the letters and numbers removed in the resulting string.

We use the

function removeLettersAndNumbers(str) {
  return str.replace(/[A-Za-z0-9]/g, '');
}
const str1 = 'number!60 ?';
const str2 = '#wel_com%e';
console.log(removeLettersAndNumbers(str1)); // ! ?
console.log(removeLettersAndNumbers(str2)); // #_%

0 (global) flag to match all the occurrences of the pattern in the string. If we don't specify this flag, only the first match of a letter or number will be removed.

Which of the following string method returns true if contains only alphabets?

Which method returns true if a string contains only letters and numbers?

What is the string method that returns true if and only if this string contains the specified sequence of char values?

Which string method will test if a string only contains alphabetic letters or digits and is at least 1 character in length?