Mongoose `findOneAndUpdate()` lets you find and modify a document atomically. Here's what you need to know.
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Mongoose populate lets you store references to other collections and load referenced documents with one line. Here's what you need to know.
Here's how you can upload files from JavaScript using Axios and JavaScript's built-in FormData class.
JavaScript lets you put any type of value in an `if` statement, not just a boolean. JavaScript's native type coercion then takes over - a "truthy" value is a value that JavaScript's native type coercion converts to true.
JavaScript has 3 logical operators: `&&`, `||`, and `!`. These 3 operators are usually used to structure `if` statements, but they also have some unique quirks that you can take advantage of. Here's what you need to know.
JavaScript type coercion is full of surprises, but if you understand the basics it can save you a lot of wasteful type checks. Here is what you need to know about falsy values.
Express automatically parses the URL query string and stores the parsed parameters in `req.query`. Here's what you need to know.
Express route parameters allow your users to pass parameters in the URL. Here's what you need to know.
Express doesn't set the request body for you by default, you need to attach middleware. Here's how you set up Express to parse the request body for you.
Express' Router class lets you define request handlers for specific URIs and HTTP methods. Here's what you need to know.
The `filter()` function in JavaScript lets you filter out array elements that don't match certain criteria. Here's what you need to know.
JavaScript doesn't have a built-in `sleep()` function, but that doesn't mean you can't pause a function in JavaScript.
The Vue cookbook recommends using Axios for HTTP requests with Vue. Here's an alternative tutorial on how to use Axios with Vue.
Cross-Origin Resource Sharing, or CORS for short, is a protocol for a browser to determine whether it is safe to make a request to a different domain. Here's what you need to know.
Plain old JavaScript objects are the most common way to store user-entered data in JavaScript. But how do you actually define a POJO?
Lodash's `clone()` function shallow clones a given object. Here's how it differs from using `Object.assign()`.
Axios' `create()` function lets you create a "template" HTTP request, with defaults for future requests.
Sending an HTTP POST request with Axios is easy. Here's what you need to know.
Express responses have a `res.json()` function that serializes a JavaScript object to JSON and puts it in the response body. Here's what you need to know.
CORS (Cross-Origin Resource Sharing) headers allow browsers to make HTTP requests to different domains. Here's how you set CORS headers with Express and Node.js
The `then()` function is the primary way you interact with promises in JavaScript, including promise chaining.
A promise is an object that represents an asynchronous operation. Promises are JavaScript's fundamental concurrency primitive - here's what you need to know.
In MongoDB, every document's `_id` property is an ObjectId by default. Here's what you need to know about ObjectIds in Mongoose.
Middleware is the fundamental building block of Express apps - even routes are middleware under the hood. Here's what you need to know about middleware.
The `instanceof` operator tells you whether a given object is an instance of a class.
As of ES6 / 2015, JavaScript has a built-in `class` keyword for object-oriented programming. Here's how it works.
The `JSON.stringify()` function is the canonical way to convert a JavaScript object to a JSON string. This tutorial explains `JSON.stringify()` from a practical perspective with examples.
The `seal()` function prevents adding or removing properties from an object, while still letting you modify existing properties. Here's what you need to know.
Lodash's `debounce()` function lets you ensure a function is only executed once every X seconds.
Lodash's `find()` function lets you find the first element in an array that matches a given criteria. Here's how it works.
In Vue, `v-bind` provides one-way data binding and lets you pass props down the component tree. Here's how it works.
In Vue, the $emit function lets you pass events up the component tree. Here's how it works.
JavaScript uses prototype-based inheritance, even when you use the ES6 class `extends` keyword. Here's what you need to know about prototypes.
In JavaScript, you often hear the terms "deep clone" and "shallow clone", also known as deep/shallow copy. This tutorial describes what these terms mean with examples.
In Mongoose, schemas are a configuration object for models. They tell Mongoose what paths to cast/validate, what options to set, and what virtuals to create.
The `mongoose.connect()` function is the most common way to connect to MongoDB with Mongoose. This tutorial describes how to use `mongoose.connect()` and how to troubleshoot common issues.
The `Object.assign()` function lets you assign properties from one object to another. You can use it to shallow copy objects or assign multiple properties at once.
You can concatenate strings in JavaScript using the `+` operator, the `Array#join()` function, or the `String#concat()` function. Here's what you need to know.
Lodash has a `get()` function that helps with safe navigation (AKA the Elvis Operator, null coalescing). In other words, get() helps you avoid "Cannot read property 'prop' of undefined" errors. Here's what you need to know.
Lodash has a `sortBy()` function that provides some neat syntactic sugar on top of `Array#sort()`. This tutorial will teach you what you need to know about `_.sortBy()`.
How to convert the string "dog" to "Dog" in JavaScript.
The void operator in JavaScript is a common source of confusion because it is rarely taught, but has a couple of convenient uses. This tutorial explains the most common use cases for the void operator.
Many frameworks, like Vue, allow you to embed JavaScript expressions in HTML. But what is an expression? Can you put `if` statements in an expression?
Error handling middleware is the canonical way to handle errors in Express. This tutorial shows you how to use error handling middleware for several common use cases.
The `res` parameter in Express is used to craft an HTTP response. This tutorial teaches you how to use the `res` object by example.
An overview of the `req` parameter in Express.
Are your Vue templates hard to read because you have extremely long template expressions in `{{}}`? This tutorial will show you how to fix this problem using computed properties.
A tutorial about how to use the `findById()` function in Mongoose.
The Mongoose `Model.find()` function finds all documents in a collection that match a query. In this tutorial, you will learn how to structure common queries in Mongoose.
The push() method adds an element to the end of a JavaScript array. This tutorial will show you how push() works.
There are two common ways to check if a JavaScript array contains a value: `includes()` and `indexOf()`. This tutorial shows you how to use both, and why you would use one versus the other.
Learn how to propagate events from a child component to a parent component using v-on.
Learn how to use the v-if directive for conditional rendering in Vue.
Two way data binding lets you build sophisticated forms without outside libraries. In this tutorial, you will learn about Vue's mechanism for two-way data binding: the v-model property.
Arrow functions let you write functions more concisely, but come with several syntactic quirks. This tutorial describes what you need to know to use arrow functions effectively.
The `const` keyword in JavaScript does not prevent you from changing an object's properties. The Object.freeze() function does that, but comes with caveats.
"use strict" enables strict mode in JavaScript. This tutorial explains what strict mode does for you.
The term "callback" can mean one of a few different concepts in JavaScript. This tutorial will help you wrap your mind around callbacks.
An introduction to how to use Object.keys() in JavaScript
An overview of the Mongoose Query class and how to use it to query for documents
A tutorial about how to get all documents in a Mongoose model
A tutorial on how to use `splice()` to add and remove elements from JavaScript arrays
There are 3 ways to get a substring of a string in JavaScript. In this tutorial, you will learn the difference between `String#substring()`, `String#substr()`, and `String#slice()`
Learn how to use Vue watchers to execute code when a value changes.
Learn how to use Vue watchers to execute code when a value changes.
Learn how to use webpack-dev-server to run your browser-side JavaScript
An introduction to using Chai with Mocha using expect and should
An introduction to using Chai with Mocha using expect and should
A brief overview of writing tests with Mocha
Learn how to upload files to Amazon S3 using the AWS Node.js SDK
WebSockets enable two-way communication between browser and server, including pushing updates to the browser. Here's how you can use websockets in Node.js
A brief introduction to Vue CLI with video
A tutorial describing the basics of Vue components: templates, data, props, and events
Learn how Webpack's watch mode (--watch) works, with examples.
Learn how to run Webpack from your Node.js scripts, no CLI required
Learn how to replace all instances of a given substring in a JavaScript string
Learn how to use the vue-template-compiler npm module to compile Vue templates
Learn how to use the built-in `Array#sort()` function in JavaScript
Learn how to use ES6 maps in JavaScript
Learn how to compare two strings in JavaScript: whether one string is greater than, less than, or equal to the other.
Learn how to handle page navigation in Vue using Vue Router
Learn how to define templates in Vue using string templates, inline templates, and single file components.
Learn how to run `webpack --watch` from your Node.js dev server using the Webpack Node API
Learn how to upload files using Express, with help from the library Formidable.
Express doesn't support promises by default. Learn what you can do about it.
Learn how to use insert a document in Mongoose if it doesn't already exist
Learn how to use Axios interceptors to make HTTP error messages readable
Learn how to check if a string contains a substring in vanilla JavaScript
Learn how to iterate nested arrays, object keys, and other values using forEach() in JavaScript
Learn how to redirect to a different URL using Express
Learn how to embed arbitrary content in Vue components using slots.
Learn about declaring and using virtuals in Mongoose.
Learn about the different ways to check if an object contains a given key in JavaScript
Learn how to use vuex, the official state management library for Vue
Learn how to enable your Express server to respond on https://localhost
Learn how to render Vue components on the server side with Express
Learn how to do HTTP basic authentication using Axios
Learn about formatting dates using the `toLocaleString()` function, with no outside libraries
Learn about the different ways to update a document in Mongoose.
Use Mathjs to calculate standard deviation in Node.js and the browser.
Learn what String valueOf(), Number valueOf(), and Date valueOf() have in common.
Learn how to understand and debug E11000 errors in Mongoose.
Learn how to get the current Unix time in JavaScript.
Learn how to set HTTP request headers on GET and POST requests with the Axios HTTP client.