Reusable javascript code snippets

data.js

export const MONTHS: Record<number, string> = {
  0: 'January',
  1: 'February',
  2: 'March',
  3: 'April',
  4: 'May',
  5: 'June',
  6: 'July',
  7: 'August',
  8: 'September',
  9: 'October',
  10: 'November',
  11: 'December',
};

export const MONTHS_SHORT: Record<number, string> = {
  0: 'Jan',
  1: 'Feb',
  2: 'Mar',
  3: 'Apr',
  4: 'May',
  5: 'Jun',
  6: 'Jul',
  7: 'Aug',
  8: 'Sep',
  9: 'Oct',
  10: 'Nov',
  11: 'Dec',
};

next.js

// Set url in middleware to be accessed inside server components:
async function middleware(request) {
    const requestHeaders = new Headers(request.headers);
    requestHeaders.set('x-url', request.url);
    return NextResponse.next({
      request: {
        headers: requestHeaders,
      },
    });
  }

// inside the server component, use it like:
const cookieStore = cookies();
const url = headers().get('x-url')!;

random-reusable-methods.js

// Given an array of keys, remove them from the object.
// returns the new object 

function removeKeys(obj, keysToRemove) {
	const newObject = {}
	Object.keys(obj).forEach(
		key => keysToRemove.includes(key) || (newObject[key] = obj[key])
	)
	return newObject
}

// Pick certain keys from an object.
// returns the new object 
function pickKeys(obj, keysToPick) {
	const newObject = {}
	Object.keys(obj).forEach(
		key => keysToPick.includes(key) && (newObject[key] = obj[key])
	)
	return newObject
}

// Given an array of keys, remove them from the list items.
// returns a new list with updated items(objects) 
function removeKeysFromListItems(list, keys) {
	return list.map(item => {
		const newObject = {}
		Object.keys(item).forEach(key => {
			const found = keys.find(keyToRemove => key === keyToRemove)
			if (!found) newObject[key] = item[key]
		})
		return newObject
	})
}

// Read contents from a text file. 
function loadFileContents() {
		// input element of type "file"
		const input = document.getElementById("file")
		// programmatic click
		input.click()

		input.addEventListener("change", () => {
			const file = input.files[0]
			const reader = new FileReader()

			reader.addEventListener("load", event => {
				const result = event.target.result
				// reusult contains the contents of the file!
			})
			if (file) {
				reader.readAsText(file)
			}
		})
	}


// display an uploaded image to html page.
// add an onchange event handler to a file input field and set it to this function
function handleUpload(e) {
	var image = document.querySelector(".image")
	image.src = URL.createObjectURL(e.target.files[0])
}

// Merge object2 in object1. All the properties of object1 will be copied to object1 
// (object2 can override object1). A new object is returned
export function mergeObjects(
	object1: Record<any, any>,
	object2: Record<any, any>
): Record<any, any> {
	const result = { ...object1 }
	for (const key in object2) {
		result[key] = { ...object2[key] }
	}

	return result
}

// divide an array into chunks of specific size. The leftover items will be added
// in the last chunk
export function getArrayChunks<T = any>(
	array: Array<any>,
	chunkSize: number
): Array<Array<T>> {
	const chunks: Array<Array<any>> = []
	let index = 0

	while (index < array.length) {
		chunks.push(array.slice(index, index + chunkSize))
		index += chunkSize
	}

	return chunks
}

// Sort Records(objects) In Arrays By Some Key.
// @PARAMS:
// data => array of objects to sort
// key => object key on which sort is based.
// order => DESC | ASC
// limit => number of objects to return in resulting array.
// @RETURN:
// The sorted array.
 export const sort = (data, key, order, limit = null) => {
  limit = limit ? limit : data.length;
  if (order == orders.ASC) {
    return data.slice(0, limit).sort(sortAsc);
  }

  if (order === orders.DESC) {
    return data.slice(0, limit).sort(sortDesc);
  }

  function sortAsc(firstRecord, secondRecord) {
    return typeof firstRecord[key] === 'string'
      ? firstRecord[key].toLowerCase() <= secondRecord[key].toLowerCase()
        ? -1
        : 1
      : firstRecord[key] <= secondRecord[key]
      ? -1
      : 1;
  }

  function sortDesc(firstRecord, secondRecord) {
    return typeof firstRecord[key] === 'string'
      ? firstRecord[key].toLowerCase() >= secondRecord[key].toLowerCase()
        ? -1
        : 1
      : firstRecord[key] >= secondRecord[key]
      ? -1
      : 1;
  }
};


/**********************************************************************
  Remove all extra spaces from a string.
**********************************************************************/
const removeExtraSpaces = str =>
  str
    .split(' ')
    .filter(s => s)
    .join(' ');


/**********************************************************************
  Check if a string is empty
**********************************************************************/
function isEmpty(str) {	
  return removeExtraSpaces(str) === ""
}


/**********************************************************************
  Check if any key's value is an empty string
**********************************************************************/
function someEmpty(obj) {
	return Object.entries(obj).some(([, value]) => {
		if (typeof value === "string" || value instanceof String) {
			return isEmpty(value)
		}
	})
}


/**********************************************************************
  See if one string (parent) starts with another string (child)
**********************************************************************/
const stringStarts = (parentString, childString) =>
  removeExtraSpaces(parentString)
    .toLowerCase()
    .startsWith(removeExtraSpaces(childString).toLowerCase());


/**********************************************************************
  See if one string (parent) includes another string (child)
**********************************************************************/
const stringIncludes = (parentString, childString) =>
  removeExtraSpaces(parentString)
    .toLowerCase()
    .includes(removeExtraSpaces(childString).toLowerCase());


/**********************************************************************
  Adjust text area height according to content without adding
  a scroll.
**********************************************************************/
function adjustTextAreaHeight() {
	textAreaElement.style.height = '1px';
	const scrollHeight = textAreaElement.scrollHeight;
	textAreaElement.style.height = `${scrollHeight}px`;
}

/**********************************************************************
  Generate a random string of provided length
**********************************************************************/
function generateRandomString(length: number): string {
  const characters =
    'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
  let result = '';

  for (let i = 0; i < length; i++) {
    const randomIndex = Math.floor(Math.random() * characters.length);
    result += characters.charAt(randomIndex);
  }

  return result;
}