I have to find a property in array of objects by value which is a list of strings.

For example I have someting like this:

const colors ={
colors-1: [{color: 'blue'}], 
colors-2: [{color: 'gray'}, {color: 'red'}], 
colors-3: [{color: 'white'}]
}

And I want to get for example property colors-2 by string which is inside array value.

Something like this:

findPropertyByValue(colors, 'red')

And output:

'colors-2'

Could You show me how to achieve this? Thank You.

CodePudding user response：

Here is how you could achieve what you want. Notice I added your object keys in quotes, because they contain -, it wouldn't work other way.

const colors = {
  "colors-1": [{ color: "blue" }],
  "colors-2": [{ color: "gray" }, { color: "red" }],
  "colors-3": [{ color: "white" }]
};

function findPropertyByValue(colors, value) {
  for (let color in colors) {
    if (colors[color].some((c) => c.color == value)) {
      return color;
    }
  }
  return ""; // if there isn't one
}
console.log(findPropertyByValue(colors, "red"));

CodePudding user response：

Here is a solution using find and some.
It takes the entries of the colors object and finds the entry which has an element with the input color.
The find returns an entry with [key,value] so to get key take the 0th element

Here I assumed that a single color has a unique key.
added the ?. before [0] (optional chaining - access only if available) so that when a color that is not found is input there will be no errors (returns undefined). || operator used to return a message like "not found" if the find step returns undefined

const colors ={
'colors-1': [{color: 'blue'}], 
'colors-2': [{color: 'gray'}, {color: 'red'}], 
'colors-3': [{color: 'white'}]
}

const findPropertyByValue = (obj,col) => Object.entries(obj).find(([k,v])=>v.some(({color}) => color===col))?.[0] || 'not found'


console.log(findPropertyByValue(colors,'white'))
console.log(findPropertyByValue(colors,'gray'))
console.log(findPropertyByValue(colors,'red'))
console.log(findPropertyByValue(colors,'blue'))
console.log(findPropertyByValue(colors,'green'))

CodePudding user response：

The below may be one possible solution to achieve the desired objective:

Code Snippet

const findPropertyByValue = (haystack, needle) => (
  Object.keys(haystack)
  .find(
    k => (haystack[k]).some(
      ({color}) => color === needle
    )
  ) || 'not found'
);

const colors ={
"colors-1": [{color: 'blue'}], 
"colors-2": [{color: 'gray'}, {color: 'red'}], 
"colors-3": [{color: 'white'}]
};

console.log('find red: ', findPropertyByValue(colors, 'red'));
console.log('find cyan: ', findPropertyByValue(colors, 'cyan'));

Explanation

• Iterate over the object's (haystack) keys
• .find in the value array an element whose color prop matches needle (the color being searched)
• If any such a match is found, then return the key
• Else, return not found

CodePudding user response：

You can try this:

const colors = {
  "colors-1": [{ color: "blue" }],
  "colors-2": [{ color: "gray" }, { color: "red" }],
  "colors-3": [{ color: "white" }],
};

function findPropertyByValue(obj, colorName) {
  return Object.entries(obj).find((entry) =>
    entry[1].some((color) => color.color === colorName)
  )?.[0];
}

console.log(findPropertyByValue(colors, "red"));
console.log(findPropertyByValue(colors, "not in list"));

And this solution will return all fields with specified color:

const colors = {
  "colors-1": [{ color: "blue" }],
  "colors-2": [{ color: "gray" }, { color: "red" }],
  "colors-3": [{ color: "white" }],
  "colors-4": [{ color: "white" }, { color: "red" }],
};

function findPropertyByValue(obj, colorName) {
  return Object.entries(obj).reduce(
    (acc, entry) =>
      entry[1].some((color) => color.color === colorName)
        ? [...acc, entry[0]]
        : acc,
    []
  );
}

console.log(findPropertyByValue(colors, "red"));
console.log(findPropertyByValue(colors, "not in list"));