Display combinations of:

Check out these examples:

1. 4-letter names
2. 5-letter names (116,640 combinations, slow...)
3. Basic math operators
4. 3-letter CSS hex colors
5. 8-bits
6. 52-pickup

Here is the JavaScript source code for the combination algorithm: (Adapted from scriptar.com/JavaScript/combine.js)

/*
Here are some examples of how you could use this code:
  alert(combinations({str: "ABC"}).join(", "));
  Displays:
  AAA, AAB, AAC, ABA, ABB, ABC, ACA, ACB, ACC,
  BAA, BAB, BAC, BBA, BBB, BBC, BCA, BCB, BCC,
  CAA, CAB, CAC, CBA, CBB, CBC, CCA, CCB, CCC
or
  alert(combinations({arr: ["AB","CD","EF"]}).join(", "));
  Displays:
  ACE, ACF, ADE, ADF, BCE, BCF, BDE, BDF
*/
var isArray = function(o) {
  return (o instanceof Array) || (Object.prototype.toString.apply(o) === "[object Array]");
},
combinations = function(args) {
  var n, inputArr = [], copyArr = [], results = [],
  subfunc = function(copies, prefix) {
    var i, myCopy = [], exprLen, currentChar = "", result = "";
    // if no prefix, set default to empty string
    if (typeof prefix === "undefined") {
      prefix = "";
    }
    // no copies, nothing to do... return
    if (!isArray(copies) || typeof copies[0] === "undefined") {
      return;
    }
    // remove first element from "copies" and store in "myCopy"
    myCopy = copies.splice(0, 1)[0];
    // store the number of characters to loop through
    exprLen = myCopy.length;
    for (i = 0; i < exprLen; i += 1) {
      currentChar = myCopy[i];
      result = prefix + currentChar;
      // if resulting string length is the number of characters of original string,
      // we have a result
      if (result.length === n) {
        results.push(result);
      }
      // if there are copies left,
      //   pass remaining copies (by value) and result (as new prefix)
      //   into subfunc (recursively)
      if (typeof copies[0] !== "undefined") {
        subfunc(copies.slice(0), result);
      }
    }
  };
  // for each character in original string
  //   create array (inputArr) which contains original string (converted to array of char)
  if (typeof args.str === "string") {
    inputArr = args.str.split("");
    for (n = 0; n < inputArr.length; n += 1) {
      copyArr.push(inputArr.slice(0));
    }
  }
  if (isArray(args.arr)) {
    for (n = 0; n < args.arr.length; n += 1) {
      copyArr.push(args.arr[n].split(""));
    }
  }
  // pass copyArr into sub-function for recursion
  subfunc(copyArr);
  return results;
};

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