Is there any pre-built method for finding all permutations of a given string in JavaScript?

Question

I\'m a newbie to the JavaScript world. As the title mentions, I want to know whether there is any pre-built method in JavaScript to find all possible permutations of a give

Answer 1

Assuming a large string to search, you could use a regular expression

to examine a set of possibles that first matches the letters and the total number of letters,

and return the matches that use the same letter set as the pattern.

//(case-insensitive)

function lettersets(str, pat){
    var A= [], M, tem,
    rx= RegExp('\\b(['+pat+']{'+pat.length+'})\\b', 'gi'),
    pattern= pat.toLowerCase().split('').sort().join('');
    while((M= rx.exec(str))!= null){
        tem= M[1].toLowerCase().split('').sort();
        if(tem.join('')=== pattern) A.push(M[1]);
    };
    return A;
}

lettersets(s, 'the').sort();