Merge pull request #328 from biswajitdas-007/javascript

String methods added

databases/mongoose.js

@@ -1,245 +0,0 @@
-/* *****************************************************************
- * Mongoose is a MongoDB object modeling tool designed to work in an asynchronous environment.
- * Mongoose supports both promises and callbacks.
- * ****************************************************************/
-
-// Import Mongoose
-const mongoose = require("mongoose");
-
-/* *****************************************************************
-    List of Mongoose Data Types:
-        String
-        Number
-        Date
-        Buffer
-        Boolean
-        Mixed
-        ObjectId
-        Array
-        Decimal128
-        Map
-        Schema
-        UUID
-    ******************************************************************/
-
-/* *****************************************************************
- * Schema
- * A schema is a blueprint for a model.
- * It defines the structure of the document, default values, validators, etc.
- * ****************************************************************/
-
-// Define schema for the a collection
-const productSchema = new mongoose.Schema({
-  name: {
-    type: String,
-    immutable: true, // This field cannot be changed after creation
-  },
-  price: {
-    type: Number,
-    min: 0, // Minimum value is 0
-    max: 10000, // Maximum value is 10000
-    required: true, // Not specifying a required field will result in validation error
-  },
-  category: {
-    type: String,
-    enum: ["fruit", "vegetable", "dairy"], // Only these values are allowed for 'category'
-  },
-  tags: [
-    // Array of String
-    {
-      type: String,
-      minLength: 2, // Minimum length of a single tag is 2
-      maxlength: 10, // Maximum length of a single tag is 10
-    },
-  ],
-  createdAt: {
-    type: Date,
-    // WRONG!
-    // default: Date.now(), // This results in the current date being set (as a static value) when the schema is compiled
-
-    // Correct!
-    default: () => Date.now(), // We instead use a getter function that returns the current date when called
-  },
-});
-
-// Create a model from the schema
-const Product = mongoose.model("Product", productSchema);
-// We can now use the model to create new documents in the 'products' collection
-
-/* *****************************************************************
- * Promises
- * ****************************************************************/
-
-Product.create({
-  name: "guava",
-  price: 10,
-  category: "fruit",
-  tags: ["green", "sweet", "fresh"],
-});
-
-Product.insertMany([
-  {
-    name: "apple",
-    price: 5,
-    category: "fruit",
-    tags: ["red", "sweet"],
-  },
-  {
-    name: "banana",
-    price: 3,
-    category: "fruit",
-    tags: ["yellow", "sweet"],
-  },
-  {
-    name: "broccoli",
-    price: 2,
-    category: "vegetable",
-    tags: ["green", "healthy"],
-  },
-  {
-    name: "milk",
-    price: 4,
-    category: "dairy",
-    tags: ["white", "healthy"],
-  },
-]);
-
-Product.find(); // Get documents in  'product' colelction
-
-Product.find({ name: "guava" }); // Get documents where name = 'guava'
-
-Product.find({ price: { $gt: 5, $lt: 10 } }); // Get documents where 5 < price < 10
-
-Product.find({ name: "banana" }).select({ name: 1, price: 1 }); // Get documents where name = 'banana' and only return name and price
-
-Product.countDocuments({ category: "vegetables" }); // Get count of documents where category = 'vegetables'
-
-Product.updateOne({ name: "guava" }, { price: 15 }); // Update the price of the document where name = 'guava' to 15
-
-Product.deleteOne({ name: "guava" }); // Delete the document where name = 'guava'
-
-Product.deleteMany({ category: "fruit" }); // Delete all documents where category = 'fruit'
-
-/* *****************************************************************
- * Aggregation
- * The aggregation pipeline refers to a specific flow of operations that processes, transforms, and returns results.
- * In a pipeline, successive operations are informed by the previous result.
- * Check out the MongoDB documentation at: https://www.mongodb.com/docs/manual/aggregation/
- * ****************************************************************/
-
-// * $match
-// The following aggration pipeline returns all products where price > 80 AND price < 120.
-let pipeline = [
-  {
-    $match: {
-      price: {
-        $gt: 80,
-        $lt: 120,
-      },
-    },
-  },
-];
-
-// or you can use:
-pipeline = [
-  {
-    $match: {
-      price: {
-        $and: [{ $gt: 80 }, { $lt: 120 }],
-      },
-    },
-  },
-];
-
-// Similarly, you can use $or:
-pipeline = [
-  {
-    $match: {
-      category: {
-        $or: [{ $eq: "fruit" }, { $eq: "vegetable" }],
-      },
-    },
-  },
-];
-
-// * $group
-// The following aggregation pipeline returns the total number of products created less than a year ago, in each category.
-pipeline = [
-  {
-    $match: {
-      date: {
-        $gte: new Date(new Date().setFullYear(new Date().getFullYear() - 1)),
-      },
-    },
-  },
-  {
-    $group: {
-      _id: "$category",
-      count: { $sum: 1 },
-    },
-  },
-];
-
-// * $sort
-// The following aggregation pipeline returns top 10 most expensive products.
-// Note: The $sort stage must come before $limit.
-pipeline = [
-  {
-    $sort: {
-      price: -1,
-    },
-  },
-  {
-    $limit: 10,
-  },
-];
-
-// * $project
-// To get the name and price of all products along with their ObjectId:
-pipeline = [
-  {
-    $project: {
-      name: 1,
-      price: 1,
-    },
-  },
-];
-
-// or you can exclude all other fields:
-pipeline = [
-  {
-    $project: {
-      category: 0, // 0 means exclude
-      tags: 0,
-      date: 0,
-    },
-  },
-];
-// Note: You may not use both 0 and 1 in the same projection
-// other than _id, which is included by default:
-pipeline = [
-  {
-    $project: {
-      _id: 0, // exclude ObjectId as well
-      name: 1,
-      price: 1,
-    },
-  },
-];
-
-// * $unwind
-// The following aggregation returns a new document for 'guava' for each of its tags.
-pipeline = [
-  {
-    $match: {
-      name: "guava",
-    },
-  },
-  {
-    $unwind: {
-      path: "$tags", // Name of array field that we want to unwind
-      includeArrayIndex: "arrayIndex", // This will add a new field 'arrayIndex' to each document
-      preserveNullAndEmptyArrays: true, // This will return a document for each tag, even if the 'tags' is null or empty
-    },
-  },
-];

languages/javascript.js

@@ -95,3 +95,9 @@ arr.reduce(callback[, initialValue])                 // Apply a function against
 arr.reduceRight(callback[, initialValue])            // Apply a function against an accumulator and each value of the array (from right-to-left) as to reduce it to a single value.
 arr.some(callback[, initialValue])                   // Returns true if at least one element in this array satisfies the provided testing function.
 arr.values()                                         // Returns a new Array Iterator object that contains the values for each index in the array.
+
+// String methods
+String.charAt(index)                                 // Returns the character at the specified index in a string.
+String.indexOf(character)                            // Returns the index of the first occurrence of a specified value in a string.
+String.substring(starting_index, ending_index)       // Returns a new string that is a subset of the original string.
+String.substring(starting_index)                     // Returns a substring from starting index to last index of string.

tools/ubuntu.sh

@@ -21,6 +21,7 @@ cat /proc/<process_id>/maps   # Show the current virtual memory usage of a Linux
 ip r # Display ip of the server
 
 lsof -i :9000 # List process running on port 9000
+kill -9 $(lsof -t -i:PORT) # Kill the process running on whichever port specified
 
 journalctl -u minio.service -n 100 --no-pager # List last 100 logs for specific service