数量子

const ghostSpeak = "booh boooooooh";
const regexpSpooky = /bo{3,}h/;
console.log(ghostSpeak.match(regexpSpooky));
// 予想される結果: Array ["boooooooh"]
const modifiedQuote = "[He] ha[s] to go read this novel [Alice in Wonderland].";
const regexpModifications = /\[.*?\]/g;
console.log(modifiedQuote.match(regexpModifications));
// 予想される結果: Array ["[He]", "[s]", "[Alice in Wonderland]"]
const regexpTooGreedy = /\[.*\]/g;
console.log(modifiedQuote.match(regexpTooGreedy));
// 予想される結果: Array ["[He] ha[s] to go read this novel [Alice in Wonderland]"]

const wordEndingWithAs = /\w+a+\b/;
const delicateMessage = "This is Spartaaaaaaa";
console.table(delicateMessage.match(wordEndingWithAs)); // [ "Spartaaaaaaa" ]

const singleLetterWord = /\b\w\b/g;
const notSoLongWord = /\b\w{2,6}\b/g;
const longWord = /\b\w{13,}\b/g;
const sentence = "Why do I have to learn multiplication table?";
console.table(sentence.match(singleLetterWord)); // ["I"]
console.table(sentence.match(notSoLongWord)); // [ "Why", "do", "have", "to", "learn", "table" ]
console.table(sentence.match(longWord)); // ["multiplication"]

const britishText = "He asked his neighbour a favour.";
const americanText = "He asked his neighbor a favor.";
const regexpEnding = /\w+ou?r/g;
// \w+ 1 つ以上の文字
// o   "o" が続く
// u?  省略可能で "u" が続く
// r   "r" が続く
console.table(britishText.match(regexpEnding));
// ["neighbour", "favour"]
console.table(americanText.match(regexpEnding));
// ["neighbor", "favor"]

const text = "I must be getting somewhere near the center of the earth.";
const greedyRegexp = /[\w ]+/;
console.log(text.match(greedyRegexp)[0]);
// "I must be getting somewhere near the center of the earth"
// テキストのすべてに一致（ピリオドを除く）
const nonGreedyRegexp = /[\w ]+?/; // 疑問符に注目
console.log(text.match(nonGreedyRegexp));
// "I"
// 一致する箇所は取りうる最も短い 1 文字