javascript - Regex remove repeated characters from a string by javascript

Question

I have found a way to remove repeated characters from a string using regular expressions.

function RemoveDuplicates() {
    var str = "aaabbbccc";
    var filtered = str.replace(/[^\w\s]|(.)\1/gi, "");  
    alert(filtered);
}

Output: abc this is working fine.

But if str = "aaabbbccccabbbbcccccc" then output is abcabc. Is there any way to get only unique characters or remove all duplicates one? Please let me know if there is any way.

Answer 1

像“这个，然后是一些东西和这个”这样的前瞻：

var str = "aaabbbccccabbbbcccccc";
console.log(str.replace(/(.)(?=.*\1)/g, "")); // "abc"

请注意，这会保留每个字符的最后一次出现：

var str = "aabbccxccbbaa";
console.log(str.replace(/(.)(?=.*\1)/g, "")); // "xcba"

没有正则表达式，保持顺序：

var str = "aabbccxccbbaa";
console.log(str.split("").filter(function(x, n, s) {
  return s.indexOf(x) == n
}).join("")); // "abcx"

Answer 2

这是一个老问题，但在 ES6 中我们可以使用Sets。代码如下所示：

var test = 'aaabbbcccaabbbcccaaaaaaaasa';
var result = Array.from(new Set(test)).join('');

console.log(result);