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mapify

Convert an array to a map

113 bytes

Usage

The mapify function converts an array into a Map object, allowing you to specify how keys and values are derived from each array item.

Parameters

  1. array: The input array to be converted into a Map.
  2. getKey: A function that determines the key for each item in the array. It receives two arguments:
    • item: The current array item.
    • index: The index of the current item in the array.
  3. getValue (optional): A function that determines the value for each item in the array. If not provided, the original array item is used as the value. It also receives two arguments:
    • item: The current array item.
    • index: The index of the current item in the array.

Return Value

Returns a new Map object where keys and values are derived from the input array using the provided mapping functions.

Example

import * as 
import _
_ from 'radashi'


const 
const fish: readonly [{
    readonly name: "Marlin";
    readonly weight: 105;
}, {
    readonly name: "Bass";
    readonly weight: 8;
}, {
    readonly name: "Trout";
    readonly weight: 13;
}]
fish = [
  {
    
name: "Marlin"
name: 'Marlin',
    
weight: 105
weight: 105,
  },
  {
    
name: "Bass"
name: 'Bass',
    
weight: 8
weight: 8,
  },
  {
    
name: "Trout"
name: 'Trout',
    
weight: 13
weight: 13,
  },
] as 
type const = readonly [{
    readonly name: "Marlin";
    readonly weight: 105;
}, {
    readonly name: "Bass";
    readonly weight: 8;
}, {
    readonly name: "Trout";
    readonly weight: 13;
}]
const


const 
const mappedByName: Map<"Marlin" | "Bass" | "Trout", {
    readonly name: "Marlin";
    readonly weight: 105;
} | {
    readonly name: "Bass";
    readonly weight: 8;
} | {
    readonly name: "Trout";
    readonly weight: 13;
}>
mappedByName = 
import _
_.
mapify<{
    readonly name: "Marlin";
    readonly weight: 105;
} | {
    readonly name: "Bass";
    readonly weight: 8;
} | {
    readonly name: "Trout";
    readonly weight: 13;
}, "Marlin" | "Bass" | "Trout", {
    readonly name: "Marlin";
    readonly weight: 105;
} | {
    readonly name: "Bass";
    readonly weight: 8;
} | {
    readonly name: "Trout";
    readonly weight: 13;
}>(array: readonly ({
    ...;
} | ... 1 more ... | {
    ...;
})[], getKey: (item: {
    ...;
} | ... 1 more ... | {
    ...;
}, index: number) => "Marlin" | ... 1 more ... | "Trout", getValue?: ((item: {
    ...;
} | ... 1 more ... | {
    ...;
}, index: number) => {
    ...;
} | ... 1 more ... | {
    ...;
}) | undefined): Map<...>
export mapify
Create a new Map instance from an array.
@see ― https://radashi.js.org/reference/array/mapify
@example 
const array = [
  { id: 1, name: 'Fred' },
  { id: 2, name: 'Annie' },
]


mapify(
  array,
  item => item.id,
  item => item.name,
)
// Map(2) { 1 => 'Fred', 2 => 'Annie' }
@version ― 12.2.0
mapify(
const fish: readonly [{
    readonly name: "Marlin";
    readonly weight: 105;
}, {
    readonly name: "Bass";
    readonly weight: 8;
}, {
    readonly name: "Trout";
    readonly weight: 13;
}]
fish, 
f: {
    readonly name: "Marlin";
    readonly weight: 105;
} | {
    readonly name: "Bass";
    readonly weight: 8;
} | {
    readonly name: "Trout";
    readonly weight: 13;
}
f => 
f: {
    readonly name: "Marlin";
    readonly weight: 105;
} | {
    readonly name: "Bass";
    readonly weight: 8;
} | {
    readonly name: "Trout";
    readonly weight: 13;
}
f.
name: "Marlin" | "Bass" | "Trout"
name) // => Map(3) {'Marlin' => { name: 'Marlin', weight: 105 }, 'Bass' => { name: 'Bass', weight: 8 }, 'Trout' => { name: 'Trout', weight: 13 }}
const 
const mappedByNameAndWeight: Map<"Marlin" | "Bass" | "Trout", 105 | 8 | 13>
mappedByNameAndWeight = 
import _
_.
mapify<{
    readonly name: "Marlin";
    readonly weight: 105;
} | {
    readonly name: "Bass";
    readonly weight: 8;
} | {
    readonly name: "Trout";
    readonly weight: 13;
}, "Marlin" | "Bass" | "Trout", 105 | 8 | 13>(array: readonly ({
    ...;
} | ... 1 more ... | {
    ...;
})[], getKey: (item: {
    ...;
} | ... 1 more ... | {
    ...;
}, index: number) => "Marlin" | ... 1 more ... | "Trout", getValue?: ((item: {
    ...;
} | ... 1 more ... | {
    ...;
}, index: number) => 105 | ... 1 more ... | 13) | undefined): Map<...>
export mapify
Create a new Map instance from an array.
@see ― https://radashi.js.org/reference/array/mapify
@example 
const array = [
  { id: 1, name: 'Fred' },
  { id: 2, name: 'Annie' },
]


mapify(
  array,
  item => item.id,
  item => item.name,
)
// Map(2) { 1 => 'Fred', 2 => 'Annie' }
@version ― 12.2.0
mapify(
  
const fish: readonly [{
    readonly name: "Marlin";
    readonly weight: 105;
}, {
    readonly name: "Bass";
    readonly weight: 8;
}, {
    readonly name: "Trout";
    readonly weight: 13;
}]
fish,
  
f: {
    readonly name: "Marlin";
    readonly weight: 105;
} | {
    readonly name: "Bass";
    readonly weight: 8;
} | {
    readonly name: "Trout";
    readonly weight: 13;
}
f => 
f: {
    readonly name: "Marlin";
    readonly weight: 105;
} | {
    readonly name: "Bass";
    readonly weight: 8;
} | {
    readonly name: "Trout";
    readonly weight: 13;
}
f.
name: "Marlin" | "Bass" | "Trout"
name,
  
f: {
    readonly name: "Marlin";
    readonly weight: 105;
} | {
    readonly name: "Bass";
    readonly weight: 8;
} | {
    readonly name: "Trout";
    readonly weight: 13;
}
f => 
f: {
    readonly name: "Marlin";
    readonly weight: 105;
} | {
    readonly name: "Bass";
    readonly weight: 8;
} | {
    readonly name: "Trout";
    readonly weight: 13;
}
f.
weight: 105 | 8 | 13
weight,
) // => Map(3) { 'Marlin' => 105, 'Bass' => 8, 'Trout' => 13 }