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Cheatsheet of JavaScript array methods with explanation:
To add/remove elements:
~ push(...items) – adds items to the end,
~ pop() – extracts an item from the end,
~ shift() – extracts an item from the beginning,
~ unshift(...items) – adds items to the beginning.
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To add/remove elements:
~ push(...items) – adds items to the end,
~ pop() – extracts an item from the end,
~ shift() – extracts an item from the beginning,
~ unshift(...items) – adds items to the beginning.
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~ splice(pos, deleteCount, ...items) – at index pos delete deleteCount elements and insert items.
~ slice(start, end) – creates a new array, copies elements from position start till end (not inclusive) into it.
~ slice(start, end) – creates a new array, copies elements from position start till end (not inclusive) into it.
~ concat(...items) – returns a new array: copies all members of the current one and adds items to it. If any of items is an array, then its elements are taken.
To search among elements:
~ indexOf/lastIndexOf(item, pos) – look for item starting from position pos, return the index or -1if not found.
~ includes(value) – returns true if the array has value, otherwise false.
~ indexOf/lastIndexOf(item, pos) – look for item starting from position pos, return the index or -1if not found.
~ includes(value) – returns true if the array has value, otherwise false.
~ find/filter(func) – filter elements through the function, return first/all values that make it return true.
~ findIndex is like find, but returns the index instead of a value.
~ findIndex is like find, but returns the index instead of a value.
To iterate over elements:
~ forEach(func) – calls func for every element, does not return anything.
To transform the array:
~ map(func) – creates a new array from results of calling func for every element.
~ sort(func) – sorts the array in-place, then returns it.
~ forEach(func) – calls func for every element, does not return anything.
To transform the array:
~ map(func) – creates a new array from results of calling func for every element.
~ sort(func) – sorts the array in-place, then returns it.
~ reverse() – reverses the array in-place, then returns it.
~ split/join – convert a string to array and back.
~ reduce(func, initial) – calculate a single value over the array by calling func for each element and passing an intermediate result between the calls.
~ split/join – convert a string to array and back.
~ reduce(func, initial) – calculate a single value over the array by calling func for each element and passing an intermediate result between the calls.
Additionally:
~ Array.isArray(arr) checks arr for being an array.
Please note that methods sort, reverse and splice modify the array itself.
These methods are the most used ones, they cover 99% of use cases. But there are few others:
~ Array.isArray(arr) checks arr for being an array.
Please note that methods sort, reverse and splice modify the array itself.
These methods are the most used ones, they cover 99% of use cases. But there are few others:
