List ​

zipWith() ​

Applies a binary function to corresponding elements of two lists and returns a new list.

• Type

• Details

The first parameter is a binary function , followed by two lists of equal length .

Returns a new list of the same length as the input lists, where .

• Example

const f = (a, b) => a + b;
zipWith(f, [1, 2, 3], [4, 5, 6]); //[5, 7, 9]

const f = (a, b) => a + b;
zipWith(f, [1, 2, 3], [4, 5, 6]); //[5, 7, 9]

zip() ​

Pairs elements from two lists into a new list of tuples.

• Type

• Details

Takes two lists of equal length.

Returns a new list of the same length as the input lists, where .

This is equivalent to zipWith((a, b) => [a, b]).

• Example

zip([1, 2, 3], [4, 5, 6]); //[[1, 4], [2, 5], [3, 6]]

zip([1, 2, 3], [4, 5, 6]); //[[1, 4], [2, 5], [3, 6]]

join() ​

Joins elements in a list into a string, separated by a given delimiter.

• Type

• Details

The first parameter is a string that serves as the delimiter. The second parameter is a list. The function returns a string that joins all the elements in the list, separated by the delimiter.

• Example

join('|', [1, 2, 3]); //"1|2|3"

join('|', [1, 2, 3]); //"1|2|3"

slice() ​

Slices a section of a list.

• Type

• Details

Takes two integers representing the start and end indices, and returns a new list containing elements within the specified range.

• Example

slice(0, 3, [1, 2, 3, 4]); //[1, 2, 3]

slice(0, 3, [1, 2, 3, 4]); //[1, 2, 3]

take() ​

Takes the first elements from a list.

• Type

• Details

Takes an integer and a list as parameters. Returns a new list containing the first elements from the given list.

• Example

take(3, [1, 2, 3, 4]); //[1, 2, 3]

take(3, [1, 2, 3, 4]); //[1, 2, 3]

takeWhile() ​

Takes elements from the beginning of a list as long as they satisfy a given predicate.

• Type

• Details

The first parameter is a predicate function , and the second parameter is a list. Elements are taken from the beginning of the list as long as they satisfy .

• Example

takeWhile((v) => v < 3, [1, 1, 4, 5, 1, 4]); //[1, 1]

takeWhile((v) => v < 3, [1, 1, 4, 5, 1, 4]); //[1, 1]

drop() ​

Drops the first elements from a list.

• Type

• Details

Takes an integer and a list as parameters. Returns a new list with the first elements removed.

• Example

drop(3, [1, 2, 3, 4]); //[4]

drop(3, [1, 2, 3, 4]); //[4]

dropWhile() ​

Drops elements from the beginning of a list as long as they satisfy a given predicate.

• Type

• Details

The first parameter is a predicate function , and the second parameter is a list. Elements are dropped from the beginning of the list as long as they satisfy .

• Example

dropWhile((v) => v < 3, [1, 4, 5, 1, 4]); //[4, 5, 1, 4]

dropWhile((v) => v < 3, [1, 4, 5, 1, 4]); //[4, 5, 1, 4]

every() ​

Checks if all elements in a list satisfy a given predicate.

• Type

• Details

Takes a predicate function and a list as parameters. Returns true if all elements in the list satisfy , and false otherwise.

• Example

every((v) => v < 3, [1, 1, 4, 5, 1, 4]); //false

every((v) => v < 3, [1, 1, 4, 5, 1, 4]); //false

some() ​

Checks if any element in a list satisfies a given predicate.

• Type

• Details

Takes a predicate function and a list as parameters. Returns true if any element in the list satisfies , and false otherwise.

• Example

some((v) => v < 3, [1, 4, 5, 1, 4]); //true

some((v) => v < 3, [1, 4, 5, 1, 4]); //true

concat() ​

Concatenates two lists.

• Type

• Details

Takes two lists and returns a new list that is a concatenation of the two.

• Example

concat([1, 2, 3], [4, 5, 6]); //[1, 2, 3, 4, 5, 6]

concat([1, 2, 3], [4, 5, 6]); //[1, 2, 3, 4, 5, 6]

concatr() ​

Concatenates two lists in reverse order.

• Type

• Details

Takes two lists and returns a new list that is a reverse concatenation of the two.

• Example

concatr([1, 2, 3], [4, 5, 6]); //[4, 5, 6

, 1, 2, 3]

concatr([1, 2, 3], [4, 5, 6]); //[4, 5, 6

, 1, 2, 3]

head() ​

Returns the first element of a list.

• Type

• Details

Takes a list and returns its first element.

• Example

head([1, 2, 3]); //1

head([1, 2, 3]); //1

tail() ​

Returns the last element of a list.

• Type

• Details

Takes a list and returns its last element.

• Example

tail([1, 2, 3]); //3

tail([1, 2, 3]); //3

dropHead() ​

Drops the first element of a list.

• Type

• Details

Takes a list and returns a new list with the first element removed.

• Example

dropHead([1, 2, 3]); //[2, 3]

dropHead([1, 2, 3]); //[2, 3]

dropTail() ​

Drops the last element of a list.

• Type

• Details

Takes a list and returns a new list with the last element removed.

• Example

dropTail([1, 2, 3]); //[1, 2]

dropTail([1, 2, 3]); //[1, 2]

includes() ​

Checks if a given element is present in a list.

• Type

• Details

Takes an element and a list, and returns true if the element is present in the list, and false otherwise.

• Example

includes(4, [1, 2, 3, 4]); //true

includes(4, [1, 2, 3, 4]); //true

reverse() ​

Reverses a list.

• Type

• Details

Takes a list and returns a new list with the elements in reverse order.

• Example

reverse([1, 2, 3]); //[3, 2, 1]

reverse([1, 2, 3]); //[3, 2, 1]

countWith() ​

Counts the number of elements in a list that satisfy a given predicate.

• Type

• Details

Takes a predicate function and a list, and returns the number of elements that satisfy .

• Example

countWith((v) => v === 5, [1, 2, 3, 4, 5, 5, 5]); //3

countWith((v) => v === 5, [1, 2, 3, 4, 5, 5, 5]); //3

count() ​

Counts the occurrences of a specific element in a list.

• Type

• Details

Takes an element and a list, and returns the number of occurrences of that element in the list.

• Example

count(5, [1, 2, 3, 4, 5, 5, 5]); //3

count(5, [1, 2, 3, 4, 5, 5, 5]); //3

pairList() ​

Pairs the first element with the rest of the elements in the list.

• Type

• Details

Takes a list and returns a pair consisting of its first element and the rest of the elements.

• Example

const [x, xs] = pairList([1, 2, 3, 4, 5]); // x=1, xs=[2, 3, 4, 5]

const [x, xs] = pairList([1, 2, 3, 4, 5]); // x=1, xs=[2, 3, 4, 5]