Iterate ​

iterate() ​

Iterates over a function with all possible combinations of arguments.

• Type

• Details

The first argument is a function, followed by arguments equal to the number of parameters of the function.

For each parameter in the function, if a normal value is passed, it indicates that there is only one possible value for that parameter. If a list is passed, all the values in the list will be considered as possibilities for that parameter.

The function will run all possible combinations of arguments and return the results as an array.

• Example

const foo = (a, b) => [a, b];
iterate(foo, [1, 2], [6, 7]);
//[[1, 6], [2, 6], [1, 7], [2, 7]]

const foo = (a, b) => [a, b];
iterate(foo, [1, 2], [6, 7]);
//[[1, 6], [2, 6], [1, 7], [2, 7]]

map() ​

Maps an array to a new array according to a rule.

• Type

• Details

The first argument is a function, and the second is a list.

The return value is a new list obtained by mapping the original list through the function.

• Example

map(add(1))([1, 2, 3]); //[2, 3, 4]

map(add(1))([1, 2, 3]); //[2, 3, 4]

flatMap() ​

Maps an array to a new array according to a rule and flattens the result.

• Type

• Details

The first argument is a function, and the second is a list.

The return value is a new list obtained by mapping the original list through the function.

Unlike map, the function should return a list, and flatMap will automatically concatenate these lists into a single list.

• Example

flatMap((v) => [v, v])([1, 2, 3]); //[1, 1, 2, 2, 3, 3]

flatMap((v) => [v, v])([1, 2, 3]); //[1, 1, 2, 2, 3, 3]

forEach() ​

Iterates over an array.

• Type

• Details

The first argument is a function, and the second is a list.

The function will iterate over each item in the list, performing the action specified by the passed-in function.

• Example

const list = [];
forEach((v) => list.push(v), [1, 2, 3]);
//list : [1, 2, 3]

const list = [];
forEach((v) => list.push(v), [1, 2, 3]);
//list : [1, 2, 3]

reduce() ​

Reduces an array to a single value according to a rule.

• Type

• Details

The first argument is a ternary function (or lower), where the first parameter represents the accumulator, the second represents the current value, and the third represents its position in the list.

The next arguments are an initial value and a list. The return value is the result after reducing the list according to the rule.

You can use the placeholder _ to indicate that the default initial value should be used.

• Example

reduce((a, b) => a + b, 0, [1, 2, 3]); //6
reduce((a, b) => a + b, _, [1, 2, 3]); //6

reduce((a, b) => a + b, 0, [1, 2, 3]); //6
reduce((a, b) => a + b, _, [1, 2, 3]); //6

fold() ​

Iteratively applies a function.

• Type

• Details

The first argument is a function, the second is the number of iterations, and the third is the initial value.

The final return value is the result of the last iteration of the function.

• Example

fold((v) => v + 1, 5, 0); //5

fold((v) => v + 1, 5, 0); //5

scan() ​

Iteratively applies a function and records the state at each step.

• Type

• Details

The first argument is the initial value, the second is a function, and the third is the number of iterations.

The final return value is a list of the results of each iteration.

• Example

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

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