Javascript Code Diary Entries

This is part of the Semicolon&Sons Code Diary - consisting of lessons learned on the job.

• Always consider event bubbling and capturing consequences of your listeners
• Anonymous functions do not work with remove event listener
• Arrow syntax is not a shorthand
• Async must be declared on nearest function even if it is anonymous
• Async v defer script tag attributes
• Await does not work on lists of promises
• Bare javascript requests will not pass CSRF tests
• Careful with this
• Distinguish between defaults replacing whole object or partially applying to just missing keys
• Do not attach listeners for DOMContentLoaded after it already fired
• Do not wipe form HTML during submit event
• Ensure sending and receiver of custom events is the same obj
• General tips
• How to debug a node process in chrome
• How to get summer time offset
• How to mock a promise chain
• How to send ENV variables from backend server to javascript in the browser
• How to throttle
• Html js event attributes need invocation
• Input vs change event
• Never assume a DOM element is available
• Never send un URI encoded parameters to your server from JavaScript
• Node programs do not exit if active event listeners
• On click does not bind to right click
• Pageload vs load events
• Precedence issues chaining async code
• Prefer defer and DOM content loaded to async
• Profiling in chrome
• Promise rejected means issue in promise code not issue with promise plumbing
• Pros and cons of standard vs object destructuring function signatures
• Push pop and replace state
• Return values from event handlers
• Send image with fetch API
• Top level code can be executing multiple times if many entry points
• Toplevel variables in vendor docs mean they are really on window
• Typescript
• Use counters or structured objects to assist debugging asynchronous loops
• What is the difference between focus and blur events
• You cannot compare dates in javascript
• You cannot use await in a constructor