aggregate-array-extensions
groupBy
Array.prototype.groupBy = function(keySelector, elementSelector, aggregateTransform)
| Parameter | Description |
|---|
| keySelector | Function that returns a value to group on |
| elementSelector | Function that is applied to each element of each group |
| aggregateTransform | Function that is applied to each group at the end of processing |
expect([1, 2, 3, 4, 5]
.groupBy(x => x % 2 === 0 ? 'even' : 'odd'))
.toEqual([
{ key: 'odd', value: [1, 3, 5] },
{ key: 'even', value: [2, 4] }
])
groupIntoObject
Array.prototype.groupIntoObject = function(keySelector, elementSelector, aggregateTransform)
| Parameter | Description |
|---|
| keySelector | Function that returns a value to group on |
| elementSelector | Function that is applied to each element of each group |
| aggregateTransform | Function that is applied to each group at the end of processing |
expect([1, 2, 3, 4, 5]
.groupIntoObject(x => x % 2 === 0 ? 'even' : 'odd'))
.toEqual({
odd: [1, 3, 5],
even: [2, 4]
})
nearestUpperBound
Array.prototype.nearestUpperBound = function(value, selector)
| Parameter | Description |
|---|
| value | Value to find nearest upper bound for |
| selector | Function to select the bounded value. The array must be sorted by this value. |
var source = [1, 2, 4, 8, 11, 32]
expect(source.nearestUpperBound(0)).toBe(-1)
expect(source.nearestUpperBound(3)).toBe(1)
expect(source.nearestUpperBound(9)).toBe(3)
expect(source.nearestUpperBound(100)).toBe(5)
nearestLowerBound
Array.prototype.nearestLowerBound = function(value, selector)
| Parameter | Description |
|---|
| value | Value to find nearest lower bound for |
| selector | Function to select the bounded value. The array must be sorted by this value. |
var source = [1, 2, 4, 8, 11, 32]
expect(source.nearestLowerBound(0)).toBe(0)
expect(source.nearestLowerBound(3)).toBe(2)
expect(source.nearestLowerBound(9)).toBe(4)
expect(source.nearestLowerBound(100)).toBe(-1)
findRange
Array.prototype.findRange = function(lower, upper, selector)
| Parameter | Description |
|---|
| lower | The lower bound |
| upper | The upper bound |
| selector | Function to select the bounded value. The array must be sorted by this value. |
var source = [1, 2, 4, 8, 11, 32]
expect(source.findRange(1, 32)).toEqual(source)
expect(source.findRange(3, 20)).toEqual([4, 8, 11])
expect(source.findRange(7)).toEqual([8, 11, 32])
expect(source.findRange(null, 7)).toEqual([1, 2, 4])
sum
Array.prototype.sum = function(selector)
| Parameter | Description |
|---|
| selector | Function to select the value to sum |
expect([1, 2, 3, 4].sum()).toBe(10)
mapIntoObject
Array.prototype.mapIntoObject = function(keySelector, valueSelector)
| Parameter | Description |
|---|
| keySelector | Function to select the key on the result object |
| valueSelector | Function to select the value to assign |
expect([
{ v: 1 },
{ v: 2 },
{ v: 3 }
].mapIntoObject(x => x.v, x => x.v * 2))
.toEqual({
1: 2,
2: 4,
3: 6
})