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25 powerful methods in JavaScript
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Why this thread?⬘ Are you learning JavaScript? Even if you are experienced, do you ever feel exhausted by the presence of so many methods?
⬙ The best approach to getting familiar is to know the use cases for these.
Here are 25 methods. Let's discuss their use cases.
The methods are,
➤ Array.prototype's
➊ forEach()
➋ map()
➌ reduce()
➍ every()
➎ filter()
➏ find()
➐ slice()
➑ splice()
➒ push()
➓ pop()
➊➊ shift()
➊➋ unshift()
➊➌ indexOf()
➊➍ findIndex()
➊➎ sort()
➤ Array.prototype's
➊ forEach()
➋ map()
➌ reduce()
➍ every()
➎ filter()
➏ find()
➐ slice()
➑ splice()
➒ push()
➓ pop()
➊➊ shift()
➊➋ unshift()
➊➌ indexOf()
➊➍ findIndex()
➊➎ sort()
➤ String.prototype's
➊➏ toLowerCase()
➊➐ toUpperCase()
➊➑ substring()
➊➒ indexOf()
20. charAt()
➋➊ trim()
➤ Math's
➋➋ floor()
➋➌ random()
➤ Global Methods
➋➍ setTimeout()
➋➎ setInterval()
➊➏ toLowerCase()
➊➐ toUpperCase()
➊➑ substring()
➊➒ indexOf()
20. charAt()
➋➊ trim()
➤ Math's
➋➋ floor()
➋➌ random()
➤ Global Methods
➋➍ setTimeout()
➋➎ setInterval()
➊ Array.prototype.forEach()
➤ Use Case
To iterate through each element in the array
Perform a task on each element
✘ Not suitable if the task is supposed to return some value
✩✩ forEach() is also available in Set.prototype and Map.prototype
➤ Use Case
To iterate through each element in the array Perform a task on each element✘ Not suitable if the task is supposed to return some value
✩✩ forEach() is also available in Set.prototype and Map.prototype
➋ Array.prototype. map()
➤ Use Case
To iterate through each element in the array
Perform a task on each element which returns a value
Returns a new array with all returned values
✘ Not suitable if the task doesn't return any value
➤ Use Case
To iterate through each element in the array Perform a task on each element which returns a value Returns a new array with all returned values✘ Not suitable if the task doesn't return any value
➌ Array.prototype.reduce()
➤ Use Case
To iterate through each element in the array
Perform a task on each element which accumulates the previous returned value with current element to return a new value
➤ Example
➀ Sum of all items
➁ Max of all items
➤ Use Case
To iterate through each element in the array Perform a task on each element which accumulates the previous returned value with current element to return a new value➤ Example
➀ Sum of all items
➁ Max of all items
➍ Array.prototype.every()
➤ Use Case
To iterate through elements in the array until a certain condition is not met
The task performed on each element must return a boolean value
✘ Stops iterating when condition is not met. Hence, it's not suitable for skipping.
➤ Use Case
To iterate through elements in the array until a certain condition is not met The task performed on each element must return a boolean value✘ Stops iterating when condition is not met. Hence, it's not suitable for skipping.
➎ Array.prototype.filter()
➏ Array.prototype.find()
➤ Use Case
To find element(s) which match a criteria
Use find() to find the first matched element
Use filter() to find all matched elements
✩✩ filter() returns a new array of matched elements
➏ Array.prototype.find()
➤ Use Case
To find element(s) which match a criteria Use find() to find the first matched element Use filter() to find all matched elements✩✩ filter() returns a new array of matched elements
➐ Array.prototype.slice()
➤ Use Case
To fetch a sub-array from a larger array
✩✩ slice() returns a new array, doesn't modify the existing array
➤ Use Case
To fetch a sub-array from a larger array✩✩ slice() returns a new array, doesn't modify the existing array
➑ Array.prototype.splice()
➤ Use Case
To replace a portion of the array with new elements
✩✩ splice() modifies the existing array
➤ Use Case
To replace a portion of the array with new elements✩✩ splice() modifies the existing array
Array.prototype's
➒ push()
➓ pop()
➊➊ shift()
➊➋ unshift()
➤ Use Case
Use push() and pop() to insert/remove elements from the end.
Use shift() and unshift() to insert/remove elements from the start.
✩✩ These methods modify the existing array
➒ push()
➓ pop()
➊➊ shift()
➊➋ unshift()
➤ Use Case
Use push() and pop() to insert/remove elements from the end. Use shift() and unshift() to insert/remove elements from the start.✩✩ These methods modify the existing array
Array.prototype's
➊➌ indexOf()
➊➍ findIndex()
➤ Use Case
To find the index of the first matched element
indexOf() does exact match (===)
findIndex() allows for custom match
➊➌ indexOf()
➊➍ findIndex()
➤ Use Case
To find the index of the first matched element indexOf() does exact match (===) findIndex() allows for custom match
➊➎ Array.prototype.sort()
➤ Use Case
To sort all elements of an array in some order
Provide a comparator to define custom order
By default sorting order is lexical
✩✩ This method modifies the existing array
➤ Use Case
To sort all elements of an array in some order Provide a comparator to define custom order By default sorting order is lexical✩✩ This method modifies the existing array
String.prototype's
➊➏ toLowerCase()
➊➐ toUpperCase()
➤ Use Case
To convert entire string to lowercase alphabets, use toLowerCase()
To convert entire string to uppercase alphabets, use toLowerCase()
✩✩ These methods returns a new string
➊➏ toLowerCase()
➊➐ toUpperCase()
➤ Use Case
To convert entire string to lowercase alphabets, use toLowerCase() To convert entire string to uppercase alphabets, use toLowerCase()✩✩ These methods returns a new string
➊➑ String.prototype.substring()
➤ Use Case
To fetch a part of the string between 2 indexes
✩✩ substring() returns a new string
➤ Use Case
To fetch a part of the string between 2 indexes✩✩ substring() returns a new string
➊➒ String.prototype.indexOf()
➤ Use Case
To find the very first occurrence of a "substring" in the original string
We can also mention from which index the occurrence should be checked
➤ Use Case
To find the very first occurrence of a "substring" in the original string We can also mention from which index the occurrence should be checked
20. String.prototype.charAt()
➤ Use Case
To fetch the character at a specific position of a string.
The character fetched is in UTF-16 and returned as a string.
➤ Use Case
To fetch the character at a specific position of a string. The character fetched is in UTF-16 and returned as a string.
➋➊ String.prototype.trim()
➤ Use Case
To remove whitespace from both ends of a string
✩✩ trim() returns a new string
➤ Use Case
To remove whitespace from both ends of a string✩✩ trim() returns a new string
➋➋ Math.floor()
➤ Use Case
To get the largest integer less than or, equals to the given number
➤ Use Case
To get the largest integer less than or, equals to the given number
➋➌ Math.random()
➤ Use Case
To get a floating-point pseudo-random number in the range of 0 to less than 1
It can be multiplied by any number to make a random number being generated in the range of 0 to less than that number
➤ Use Case
To get a floating-point pseudo-random number in the range of 0 to less than 1 It can be multiplied by any number to make a random number being generated in the range of 0 to less than that number
➋➍ setTimeout()
➤ Use Case
To execute a function or, piece of code after a timer expires
The code is executed only once.
✘ It is an asynchronous function. It shouldn't be used where pausing of execution is intended.
➤ Use Case
To execute a function or, piece of code after a timer expires The code is executed only once.✘ It is an asynchronous function. It shouldn't be used where pausing of execution is intended.
➋➎ setInterval()
➤ Use Case
To execute a function or, piece of code repeatedly with a fix time delay
✘ The code is ensured to be executed each time after the time delay. But not "exactly" after the time delay.
✩✩ Cancel further execution using clearInterval()
➤ Use Case
To execute a function or, piece of code repeatedly with a fix time delay✘ The code is ensured to be executed each time after the time delay. But not "exactly" after the time delay.
✩✩ Cancel further execution using clearInterval()
Tasks for youFind use cases of below
➤ String.prototypes's
❍ startsWith() / endsWith()
❍ fromCharCode()
❍ padStart() / padEnd()
❍ repeat()
❍ match() / matchAll()
❍ replace() / replaceAll()
➤ Math's
❍ ceil()
❍ trunc()
❍ round()
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