after.json

{
  "id": "0adfd74a-15a7-11e7-fa42-91cf3a1e0138",
  "handle": "in",
  "has_variants": false,
  "variant_parent_id": "0adfd74a-15a7-11e7-fa42-7a8da948e8d9",
  "active": true,
  "name": "Sleek Rubber Ball",
  "base_name": "Sleek Rubber Ball",
  "description": "Et iure nulla pariatur odit vel veritatis.",
  "images": null,
  "sku": "47544",
  "supply_price": "8.00",
  "track_inventory": true,
  "inventory": [
  ],
  "price_book_entries": [
    {
      "id": "4fbd5791-4183-5180-7165-cd9cbbf654b2",
      "product_id": "0adfd74a-15a7-11e7-fa42-91cf3a1e0138",
      "price_book_id": "8d4918f4-4df1-11e2-b1f5-4040782fde00",
      "price_book_name": "General Price Book (All Products)",
      "type": "BASE",
      "customer_group_id": "8d464ce3-4df1-11e2-b1f5-4040782fde00",
      "price": 18,
      "loyalty_value": null,
      "tax": 1.08,
      "tax_id": "0adfd74a-15a7-11e7-fa42-91b2fb4d898b",
      "tax_rate": 0.06,
      "tax_name": "Normal Sales Tax",
      "display_retail_price_tax_inclusive": 0
    }
  ],
  "price": 18,
  "tax": 1.08,
  "tax_id": "0adfd74a-15a7-11e7-fa42-91b2fb4d898b",
  "tax_rate": 0.06,
  "tax_name": "Normal Sales Tax",
  "taxes": null,
  "display_retail_price_tax_inclusive": 0,
  "updated_at": "2017-09-04 17:14:47"
}

before.json

{
  "id": "0adfd74a-15a7-11e7-fa42-91cf3a1e0138",
  "source_id": "",
  "variant_source_id": "",
  "handle": "in",
  "type": "",
  "has_variants": false,
  "variant_parent_id": "0adfd74a-15a7-11e7-fa42-7a8da948e8d9",
  "variant_option_one_name": "",
  "variant_option_one_value": "",
  "variant_option_two_name": "",
  "variant_option_two_value": "",
  "variant_option_three_name": "",
  "variant_option_three_value": "",
  "active": true,
  "name": "Sleek Rubber Ball",
  "base_name": "Sleek Rubber Ball",
  "description": "Et iure nulla pariatur odit vel veritatis.",
  "image": "",
  "image_large": "",
  "images": null,
  "sku": "47544",
  "tags": "",
  "brand_id": "",
  "brand_name": "",
  "supplier_name": "",
  "supplier_code": "",
  "supply_price": "8.00",
  "account_code_purchase": "",
  "account_code_sales": "",
  "track_inventory": true,
  "button_order": "",
  "inventory": [
  ],
  "price_book_entries": [
    {
      "id": "4fbd5791-4183-5180-7165-cd9cbbf654b2",
      "product_id": "0adfd74a-15a7-11e7-fa42-91cf3a1e0138",
      "price_book_id": "8d4918f4-4df1-11e2-b1f5-4040782fde00",
      "price_book_name": "General Price Book (All Products)",
      "type": "BASE",
      "outlet_name": "",
      "outlet_id": "",
      "customer_group_name": "",
      "customer_group_id": "8d464ce3-4df1-11e2-b1f5-4040782fde00",
      "price": 18,
      "loyalty_value": null,
      "tax": 1.08,
      "tax_id": "0adfd74a-15a7-11e7-fa42-91b2fb4d898b",
      "tax_rate": 0.06,
      "tax_name": "Normal Sales Tax",
      "display_retail_price_tax_inclusive": 0,
      "min_units": "",
      "max_units": "",
      "valid_from": "",
      "valid_to": ""
    }
  ],
  "price": 18,
  "tax": 1.08,
  "tax_id": "0adfd74a-15a7-11e7-fa42-91b2fb4d898b",
  "tax_rate": 0.06,
  "tax_name": "Normal Sales Tax",
  "taxes": null,
  "display_retail_price_tax_inclusive": 0,
  "updated_at": "2017-09-04 17:14:47",
  "deleted_at": ""
}

Omit all empty string values with underscore

var _ = require('underscore');

var omitEmptyValues = function omitEmptyValues(data) {
  if(!_.isObject(data)) {
    return data;
  }
  else {
    if (_.isArray(data)) {
      var clone = [];
      _.each(data, function(value) {
        if (_.isObject(value)) {
          clone.push(omitEmptyValues(value));
        }
        else if (_.isString(value) && value.trim() !== '') {
          clone.push(value);
        }
        else if (!_.isString(value)) {
          clone.push(value);
        }
      });
      return clone;
    }
    else if (_.isObject(data)) {
      var clone = {};
      _.each(data, function(value, key) {
        if (_.isObject(value)) {
          clone[key] = omitEmptyValues(value);
        }
        else if (_.isString(value) && value.trim() !== '') {
          clone[key] = value;
        }
        else if (!_.isString(value)) {
          clone[key] = value;
        }
      });
      return clone;
    }
    else {
      return data;
    }
  }
};