Array

Check whether array empty

• No need to check whether array is undefind anymore, just use null conditional operator.

if (array !=== undefined && array.length != 0){}

if (array?.length){}

forEach

array.forEach( () => {} )

filter

array.filter( () => {} )

Check whether an array contains all the elements in another array (tag check)

required_tags = ['A', 'B']
doc_tags = ['A', 'B', 'C']

if (requried_tags.every((tag) => doc_tags.includes(tag)))

Custom attribute

HTML element are all just javascript objects, we can add custom attributes on it if needed.

The convention is to add ‘data-’ prefix on the attribute name.

let tagButtonsContainer = document.getElementsByClassName("tagSearch-tags");
tagButtonsContainer.searchTags = [];

Javascript object vs JSON

Unlike JSON, in JS, we don’t need to wrap object keys in double quotes.