concat with space js code example

Example 1: replace multiple spaces with single space javascript

string = string.replace(/\s\s+/g, ' ');

Example 2: js string insert space

document.getElementById('iban').addEventListener('input', function (e) {
  e.target.value = e.target.value.replace(/[^\dA-Z]/g, '').replace(/(.{4})/g, '$1 ').trim();
});