正则表达式通过javascript从字符串中删除重复的字符

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

A lookahead like "this, followed by something and this":

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

Note that this preserves the last occurrence of each character:

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

Without regexes, preserving order:

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

Answer 2

This is an old question, but in ES6 we can use Sets . The code looks like this:

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