CODEWITHSUNDEEP
javascriptnode.js
baao
baao

Reputation: 73241

More efficient way of string creation

I have the following object and need this string:

product_name,@dummy1,@dummy2,seller_sku,@price,item_quantity,@dummy6,@dummy7,@dummy8,@dummy9,@dummy10,@dummy11,@dummy12,@dummy13,@dummy14,@dummy15,@dummy16,@dummy17,@dummy18,@dummy19,@dummy20,@dummy21,@dummy22,@dummy23,@dummy24,@dummy25,fulfillment_channel

{ 
  countFields: 27,
  fields: 
   { product_name: 0,
     seller_sku: 3,
     price: 4,
     item_quantity: 5,
     fulfillment_channel: 26 
   } 
}

The object and the string (including length) are subject to change.

I create the string like this (using lodash):

function tableString(fields){
    var obj = _.invert(fields.fields);
    obj.length = fields.countFields;
    var values = Array.prototype.slice.apply( obj );
    var arr = _.merge(new Array(fields.countFields),values).map(function(val,i){
        if (val == 'price' || !~values.indexOf(val)) {
            if (val == 'price') {
                return '@price';
            }
            return '@dummy' + i;
        }
        return val;
    }); 

    return arr.join(',');
}

var first = { 
  countFields: 27,
  fields: {
     product_name: 0,
     seller_sku: 3,
     price: 4,
     item_quantity: 5,
     fulfillment_channel: 26 
  } 
}
                                                              
console.log(tableString(first));
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/3.10.1/lodash.min.js"></script>

I would like to avoid the map()/array functions at the end. Does someone find an easier way to create above string from the object?

Upvotes: 3

Views: 97

Answers (1)

Joe
Joe

Reputation: 8272

I don't know if this is easier but you get a string at the end and its vanilla javascript.

function tableString(fields){
    var reversedFields = {};
    for(var key in fields.fields){ // we swapped key and value
        reversedFields[fields.fields[key]] = key;
    }

    for(var i=0,x=fields.countFields-1,result = "";i<fields.countFields;i++){
        if(reversedFields[i]){
            result += (reversedFields[i] == 'price' ? '@price' : reversedFields[i]);
        } else {
            result += '@dummy' + i;
        }
        if(i < x){
            result += ",";
        }
    }

    return result;
}

var res = tableString({
    countFields: 27,
    fields:{
        product_name: 0,
        seller_sku: 3,
        price: 4,
        item_quantity: 5,
        fulfillment_channel: 26
    }
});

// result product_name,@dummy1,@dummy2,seller_sku,@price,item_quantity,@dummy6,@dummy7,@dummy8,@dummy9,@dummy10,@dummy11,@dummy12,@dummy13,@dummy14,@dummy15,@dummy16,@dummy17,@dummy18,@dummy19,@dummy20,@dummy21,@dummy22,@dummy23,@dummy24,@dummy25,fulfillment_channel

Upvotes: 3

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