EN
TypeScript - Array reduce() method example
11 points
In TypeScript it is possible to convert array using reduce method in following ways.
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let array = [2
{3
id : 1,4
group : 'Juices',5
items : [6
{ name : 'Apple', price : 1.4 },7
{ name : 'Orange', price : 1.7 }8
]9
},10
{11
id : 2,12
group : 'Baking',13
items : [14
{ name : 'Bread', price : 1.3 },15
{ name : 'Roll', price : 0.5 },16
{ name : 'Loaf', price : 1.1 }17
]18
},19
{20
id : 3,21
group : 'Meat',22
items : [23
{ name : 'Salmon', price : 15.0 },24
{ name : 'Turey', price : 6.5 },25
{ name : 'Chicken', price : 7.8 }26
]27
},28
];29
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let reduce = (array : Array<any>, entry : any, index : number) : Array<any> => {31
[array, entry.items];32
};33
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let products = array.reduce(reduce, new Array<any>());35
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console.log(products);Where:
array.reduce(reduce, new Array<any>())method has been used to convert array of groups to array of items with initial empty array (secondreducemethod argument),let reduce = (array : Array<any>, entry : any) : Array<any> ...method contains conversion and merging logic for each array element
where:array : Array<any>variable indicates array returned during previous iteration ornew Array<any>()object if it is first iteration,entry : anyvariable contains currently iterated element,
Output (with NodeJS):
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[2
{ name: 'Apple', price: 1.4 },3
{ name: 'Orange', price: 1.7 },4
{ name: 'Bread', price: 1.3 },5
{ name: 'Roll', price: 0.5 },6
{ name: 'Loaf', price: 1.1 },7
{ name: 'Salmon', price: 15 },8
{ name: 'Turey', price: 6.5 },9
{ name: 'Chicken', price: 7.8 } 10
]xxxxxxxxxx1
let array = [2
{3
id : 1,4
group : 'Juices',5
items : [6
{ name : 'Apple', price : 1.4 },7
{ name : 'Orange', price : 1.7 }8
]9
},10
{11
id : 2,12
group : 'Baking',13
items : [14
{ name : 'Bread', price : 1.3 },15
{ name : 'Roll', price : 0.5 },16
{ name : 'Loaf', price : 1.1 }17
]18
},19
{20
id : 3,21
group : 'Meat',22
items : [23
{ name : 'Salmon', price : 15.0 },24
{ name : 'Turey', price : 6.5 },25
{ name : 'Chicken', price : 7.8 }26
]27
},28
];29
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let reduce = (result : any, entry : any, index : number) : any => {31
if(entry.items.length < result.items.length)32
return entry;33
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return result;35
};36
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let smallestGroup = array.reduce(reduce);38
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console.log(smallestGroup);Output (with NodeJS):
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{2
id: 1,3
group: 'Juices',4
items: [5
{ name: 'Apple', price: 1.4 },6
{ name: 'Orange', price: 1.7 }7
]8
}