const regex = /(?:\baccord\b|\G(?<!^))[^)\s]*\K\s+/gm;
// Alternative syntax using RegExp constructor
// const regex = new RegExp('(?:\\baccord\\b|\\G(?<!^))[^)\\s]*\\K\\s+', 'gm')
const str = `A scripture reference like [Luke 2:12, 16](accord://read/?Luke 2:12, 16) should be clickable.`;
const subst = `%20`;
// The substituted value will be contained in the result variable
const result = str.replace(regex, subst);
console.log('Substitution result: ', result);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for JavaScript, please visit: https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions