Check array of strings against array of objects and return something per each case

Question

I have a simple array problem: I have two different arrays: one with strings and one with objects. I need to check one agains the other in a certain way: Array of objects needs to check if a property of the object is included in array of strings, and return a response in each case.

const colors = ["blue", "pink", "red", "green", "yellow", "orange", "white"]

const objColors = [{name:"pink", value: true}, {name:"green", value: true}, {name: "white", value: false}]

My expected response array would be something like:

const res = [false, true, false, true, false, false, false]

I don't know how to tackle this, as I've tried several things with no success. I tried double iterations, but it gave me a wrong response. I've also tried the method includes, but then I can only check my objColors array, therefore I don't get a response for all the cases I need to check

let res = objects.map(x => (strings.includes(x.name)))

Could someone please give me a hint on how to check them to get the desired response? Thanks in advance

CertainPerformance · Accepted Answer · 2022-01-22 18:42:25Z

1

First turn the array of objects into a structure that's easier to check through - perhaps a Map, or a Set of the values that are true. Then you can map the colors array and look up the associated value.

const colors = ["blue", "pink", "red", "green", "yellow", "orange", "white"];
const objColors = [{name:"pink", value: true}, {name:"green", value: true}, {name: "white", value: false}];


const trueColors = new Set(
  objColors
    .filter(({ value }) => value)
    .map(({ name }) => name)
);
const res = colors.map(color => trueColors.has(color));
console.log(res);

answered Jan 22, 2022 at 18:42

CertainPerformance

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1 Comment

ihatepineapple Over a year ago

Thanks for your answer! It works but most importantly, it prompted me to watch some videos on the Set property and learn a little more, so thank you very much

Nina Scholz · Accepted Answer · 2022-01-22 18:50:43Z

1

An approach with an object.

const
    colors = ["blue", "pink", "red", "green", "yellow", "orange", "white"],
    objColors = [{ name: "pink", value: true }, { name: "green", value: true }, { name: "white", value: false }],
    wanted = Object.fromEntries(objColors.map(({ name, value }) => [name, value])),
    result = colors.map(c => !!wanted[c]);

console.log(result);

answered Jan 22, 2022 at 18:50

Nina Scholz

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1 Comment

ihatepineapple Over a year ago

Thanks! I was not familiar with the fromEntries method and I found it very practical as well

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