MongoDB upsert index

upsertIndex.js

/*

Please advise me better coding style and syntax, thanks!

Process Flow:
1. prepare readyToCreateIndexes which contains one or more indexes
2. get all current indexes and compare keyName and key field
- keyName
  - not exist:
    - fields different, insert!
    - fields the same, drop older or ignore new one, depend on your choice
  - exist:
    - fields different, drop older index and create new one
    - fields the same, ignore this index creation
3. drop duplicated indexes and trim non-needed indexes of this creation
4. create index
*/

use somedb;

var Process = {

    collectionName: "someCollection",
    readyToCreateIndexes: [
        { key: { fieldA: 1, fieldB: 1, fieldC: -1 }, name: "fieldA_1_fieldB_1_fieldC_-1" }
    ],
    getCollection: function() {
        let that = this;
        return db.getCollection(`${that.collectionName}`);
    },
    dropIndex: function(toDeletedIndexNames){
        let that = this;
        print(`\n==========   Drop duplicated indexes  ============`);
        print(`${toDeletedIndexNames}`);

        db.runCommand({
            dropIndexes: `${that.collectionName}`,
            index: toDeletedIndexNames
        });
    },
    createIndex: function(){
        let that = this;
        print(`\n==========       Create indexes       ============`);
        if (this.readyToCreateIndexes.length == 0) return;
        print(`${JSON.stringify(this.readyToCreateIndexes)}`);

        db.runCommand({
            createIndexes: `${that.collectionName}`,
            index: this.readyToCreateIndexes
        });
    },
    getCurrentIndexes: function (){

        let that = this;
        var bson = this.getCollection().getIndexes();
        var json = JSON.stringify(bson);
        var obj = JSON.parse(json);
        var dict = new Object();
        dict = {};

        for(var itr = 0 ; itr < obj.length ; itr++)
        {
            dict[obj[itr].name] = JSON.stringify(obj[itr].key);
        }

        return dict;
    },
    getExistedIndexes: function (dict){

        let that = this;
        var needDeleteIndexes = [];
        var spliceIndex = [];
        print(`\n==========    Skip existed indexes    ============`);

        for(var itr in this.readyToCreateIndexes){
            let createName = this.readyToCreateIndexes[itr].name;
            let createKey = JSON.stringify(this.readyToCreateIndexes[itr].key);

            for(var keyName in dict){

                if (createName == keyName && createKey == dict[keyName]) {
                    //print(`1. ${createName}, ${createKey}`);
                    spliceIndex.push(itr);
                    continue;
                }

                if (createName == keyName && createKey != dict[keyName]) {
                    //print(`2. ${createName}, ${createKey}`);
                    needDeleteIndexes.push(createName);
                    continue;
                }

                if (createName != keyName && createKey == dict[keyName]) {
                    //print(`3. ${createName}, ${createKey}`);
                    needDeleteIndexes.push(keyName);
                    continue;
                }
            }
        }

        // Remove already existed indexes from create list
        let offset = 0;
        for(var toSkip in spliceIndex){
            toSkip -= offset;
            this.readyToCreateIndexes.splice(toSkip,1);
            offset++;
        }

        return needDeleteIndexes;
    },
    upsertIndex: function(){
        let that = this;

        // Get current Indexes
        let dict = this.getCurrentIndexes();

        // Get duplicated with exist index name
        var toDeletedIndexNames = this.getExistedIndexes(dict);

        // Drop duplicated indexes
        this.dropIndex(toDeletedIndexNames);

        // Create indexes
        this.createIndex();

        print(`\n==========        reIndex done        ============`);
    }
};

Process.upsertIndex();