compare array of object with array of strings

Question

I have 2 arrays:

First array is array of strings:

let array1 = ['value1', 'value2', 'value3', 'value4', 'value5']

second is array of objects that can vary, meaning sometimes I will have all the values sometimes only some and they will not be sorted. Something like this:

array2 = [
{
property1: 'value1',
property2: 42,
property3: 'some other value'
},

{
property1: 'value3',
property2: 342,
property3: 'some other value'
},

{
property1: 'value5',
property2: 422,
property3: 'some other value'
}
]

I need to make another array. If there is value1 from first array inside array2 I need to push to newly created array property2, if not I need to push 0. Order of the items needs to be the same as the array 1 meaning that in the end I will have an array that looks like this:

array3 = [42, 0, 342, 0, 422]

Thanks

I have looked up on stackoverflow but no solution worked for me

Answer 1

• Using Array#reduce, iterate over array2 while updating a Map where the key is property1 and the value is property2
• Using Array#map, iterate over array1 to return the value of each item from the above Map, 0 otherwise

const 
  array1 = ['value1', 'value2', 'value3', 'value4', 'value5'],
  array2 = [ { property1: 'value1', property2: 42, property3: 'some other value' }, { property1: 'value3', property2: 342, property3: 'some other value' }, { property1: 'value5', property2: 422, property3: 'some other value' } ];

const valueMap = array2.reduce((map, { property1, property2 }) => map.set(property1, property2), new Map);

const array3 = array1.map(value => valueMap.get(value) ?? 0);

console.log(array3);

Answer 2

So you want to find all the property2 values where the property1 value exists in another array...
A forEach with a push to your result array (array3) should do it:

const array1 = ['value1', 'value2', 'value3', 'value4', 'value5']

const array2 = [{
    property1: 'value1',
    property2: 42,
    property3: 'some other value'
  },

  {
    property1: 'value3',
    property2: 342,
    property3: 'some other value'
  },

  {
    property1: 'value5',
    property2: 422,
    property3: 'some other value'
  }
]


let array3 = []
array2.forEach(item => {
  if (array1.includes(item.property1)) {
    array3.push(item.property2)
  }
})
console.log(array3);

As other comments say, please remember to include the things you have tried when posting the question.

P.S: be careful when posting your code, there were some missing commas, making the syntax invalid