Match Characters that Occur Zero or More Times

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#js #正则表达式

本文详细解析了正则表达式中*与+符号的功能差异，通过实例展示了*允许匹配字符出现任意次，包括0次，而+至少要求字符出现一次。文章通过JavaScript代码演示了如何使用这两个符号来匹配字符串中的重复字符。

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Any letter in a regex expression that is followed by a * does not have to occur in the string tested whereas any letter in a regex expression followed by a + must occur in a string at least once, as shown below,

let phrase = "ba humbug";

let regexPlus = /bah+/;
let regexStar = /bah*/;

regexPlus.test(phrase);  // returns false
regexStar.test(phrase);  // returns true

Both allow for any number of occurrences of the same letter in a row, for example,

let phrase = "wooooow look at that!";

let regexPlus = /wo+w/;
let regexStar = /wo*w/;

regexPlus.test(phrase); // returns true
regexStar.test(phrase); // returns true

example:

Create a regex chewieRegexthat uses the *character to match all the upper and lower"a"characters in chewieQuote. Your regex does not need flags, and it should not match any of the other quotes.

let chewieQuote = "Aaaaaaaaaaaaaaaarrrgh!";
let chewieRegex = /change/; // Change this line
let result = chewieQuote.match(chewieRegex);

let chewieQuote = "Aaaaaaaaaaaaaaaarrrgh!";
let chewieRegex = /Aa*/; 
let result = chewieQuote.match(chewieRegex);