Check Whether a String Starts with a Regexp in JavaScript
Dec 24, 2021
To check the beginning of a string using a regular expression in JavaScript, use the test() function and a regular expression that starts with ^.
The ^ character is a special character that represents the start of the string.
The test() function will search the string and return true if the string contains a match.
/^A/.test('A beautiful day for a walk, no?'); // true
/^A/.test('What a beautiful day'); // falseYou can also turn a string into a regular expression by using the new RegExp() constructor.
const string = '^Hello';
const regexp = new RegExp(string);
regexp.test('Hello World'); // true
regexp.test('Hi There'); // falseCase Insensitive Search
The i flag makes a regular expression case insensitive.
/^A/i.test('ABC'); // true
/^A/i.test('abc'); // true
/^A/i.test('bac'); // false
// Or using RegExp constructor
const regexp = new RegExp('^A', 'i');
regexp.test('ABC'); // true
regexp.test('abc'); // true
regexp.test('bac'); // false
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