我想按字母顺序生成唯一的字母键| angularJs

Question

I want to generate keys in alphabetical order in such a way that it begins with

aaaaa

then the next would be aaaab and after reaching to aaaaz the string should be aaaba and then aaabb and so on , so that the keys generate properly

My sample JSON to be created

 var keygen={aaaaa,
             aaaab,
             aaaac .........aaaaz,aaaba ....}

my javascript

$scope.doKeyGen=function(lastValueInJSON)
                {  // Do something 
                   }

Answer 1

This will work for you. JS Fiddle is here.

https://jsfiddle.net/3d789okv/7/

Make sure that you the last value you give will be hit. Otherwise you are going to an infinite loop hell. Also you can configure the number of letters in the call to getNext(). But make sure that you set the equal number of letters in the first value and "aaaaa" and the last value "asxas"

 String.prototype.replaceAt=function(index, replacement) {
        return this.substr(0, index) + replacement+ this.substr(index + replacement.length);
    }

 var json = [];
 function getNext(charCount,lastValue){
    changeIndex = charCount -1;
   var newValue = "";
     while (changeIndex >= 0){
        if(lastValue[changeIndex] !== "z"){
           var changed = lastValue[changeIndex];
           var replacechanged = String.fromCharCode(changed.charCodeAt(0)+1);
           newValue = lastValue.replaceAt(changeIndex,replacechanged)
           for(var j=changeIndex+1; j < charCount; ++j){
              newValue = newValue.replaceAt(j,"a");
           }
           return newValue;
         }
         changeIndex--;
      }
 }

 function createJSON(lastValue){
    if(!json.length){
      //var startPrefix = "aaaaa";
      json.push("aaaaa");
      while(lastValue !== json[json.length-1]){

         json.push(getNext(5,json[json.length-1]));
      }
      console.log(json);
    }
 }

 createJSON("aaabz");

Answer 2

You need to use recursive function to generate your keys. I've written some piece of code in this fiddle link , which generate keys as per your requirement and create JSON too.

Please note I assume small case alphabets keys only. and used 3 length string (aaa), You can use 4 length also but performance degrades.

You can change any first key in input in attached fiddle, like 'aay' then code generate next all possible keys.(aaz, aba,.....,zzz).

Answer 3

You can use this

 function getNextKey(lastKeyCode, changeIndex) { var charCodes = []; if( changeIndex == undefined ) changeIndex = lastKeyCode.length - 1; if(changeIndex - 1 > -1 && lastKeyCode.charCodeAt(changeIndex) == 122 ) { lastKeyCode = getNextKey(lastKeyCode, changeIndex - 1); } lastKeyCode.split('').forEach(function(e){charCodes.push(e.charCodeAt())}); charCodes[changeIndex] = 97 + (charCodes[changeIndex] - 96 ) % 26; return String.fromCharCode.apply(0, charCodes); } //-------------------EDIT ( GENERATE KEYS LIKE THIS )------------ function generateKeys(lastKey) { var json = []; var nextKey = new Array(lastKey.length + 1 ).join('a'); json.push(nextKey); while( nextKey != lastKey ) { json.push( (nextKey = getNextKey(nextKey)) ) } return json; } //---------------------------Example---------------------------- var last = 'test'; console.log('Last Key : '+last+' | Generated key length : '+generateKeys(last).length);