how to check first 3 numbers in js using regx code example

Example 1: get only numbers regex javascript

var numberPattern = /\d+/g;

'something102asdfkj1948948'.match( numberPattern )

Example 2: javascript regex Zero or one occurrence

// javascript regex Zero or one occurrence
let neighbor = /neighbou?r/;
console.log(neighbor.test("neighbour")); // true
console.log(neighbor.test("neighbor")); // true

Example 3: javascript regex One or more occurrences of the pattern

// Regular expression 1 or more occurrences of the pattern
console.log(/'\d+'/.test("'123'")); // true
console.log(/'\d+'/.test("''")); // false

let cartoonCrying = /boo+(hoo+)+/i;
console.log(cartoonCrying.test("Boohoooohoohooo"));// true