Find Value in an Array

Find a value in an array of objects in Javascript

You can loop over the array and test for that property:

function search(nameKey, myArray){
    for (var i=0; i < myArray.length; i++) {
        if (myArray[i].name === nameKey) {
            return myArray[i];
        }
    }
}

var array = [
    { name:"string 1", value:"this", other: "that" },
    { name:"string 2", value:"this", other: "that" }
];

var resultObject = search("string 1", array);

How to search for a specific value in an array of objects based on another value [JavaScript]?

To find the element

const arr = arr.find(p => p.property == someValue);

This will return undefined if the element is not found and return the element if found.

To find the index of the element

If you only want the index use findIdex

const index = arr.findIndex(p => p.property == someValue);

If the element is not found it will return -1 and if found return the index.

To check if the element is present i.e bool value

Your current implementation does that. You can simply return that.

return posts.some(e => e.Permission === true && e.Id == PostId)

Seems like you are confusing with how to use the value from somewhere else to search in the array, you can always pass in a callback and check that.

value => value.somProp == value1 && value.otherProp == value2 || someOtherChek(value)

Find the value inside the array of objects that include children from the array of objects

Because you have a nested structure, you can't use .filter to get all nested objects - .filter will only return to you the matching objects on the topmost level. Instead, define an empty array on the initial call, then push to that array when an item passes the test, and pass the array around to each recursive call. Finally, return that array:

var array=[{id:1,value:'value',children:null},{id:2,value:'my value',children:[{id:'child1',value:'my value',children:null},{id:'child2',value:'value',children:null},{id:'child3',value:'value',children:[{id:'childchild1',value:'my value',children:null}]}]},{id:3,value:'value',children:null},{id:4,value:'my value'}];

function find(searchData, target, accum=[]){

  target.forEach((f)=>{

    if(f.children){

      find(searchData, f.children, accum)

    }

    if(f.value.includes(searchData)){

      accum.push(f);

    }

  });

  return accum;

}

console.log(find('my', array));

JAVA: Finding Values in an Array

for(i = 0; i < NUM_VALS; ++i) {
   if(userValues[i] == matchValue) {
      //numMatches = i;   //WRONG
      numMatches++;     //Correct
   }
}

This block is incorrect, you are assigning numMatches to the index value of the array rather, it should have been that if there's a match increment values of numMatches by 1.

Javascript search an array for a value starting with a certain value

You can use the find() function which allows you to pass a custom function in parameter that will be tested on each value. This way you can use startsWith() on each value of the array as you intended to do.

Example:

const array1 = ['abc','xyz'];

function findStartWith(arg) {
  return array1.find(value => {
    return arg.startsWith(value);
  });
}

console.log(findStartWith("hello")); // undefined
console.log(findStartWith("abcd")); // abc
console.log(findStartWith("xyzz")); // xyz

Can I update an array of objects by modifiying a value return by array.find()?

Find just finds the first element in the array, they do not edit the element, but find the element. So when you have the element, you can edit afterward, but you do not have the index of the element inside the array, so you will need the index too if you want to pass the edited element in the array.

You have multiple ways to update. If you want a shorter way, right now it came into my mind like this :

   setArray((oldState) =>
      oldState.map((item) => {
        if (item.value === "one") {
          return {
            value: "asdasd"
          };
        }
        return {...item};
      })
    );

So directly you can set the value inside setArray why? because the map returns a new array.
Or you can write more readable :

 const newState = array.map((item) => {
        if (item.value === "one") {
          return {
            value: "asdasd"
          };
        }
        return {...item};
      });
    setArray(newState)

A similar question can be found here

If you have any questions ask. Thanks.

How to find the array index with a value?

You can use indexOf:

var imageList = [100,200,300,400,500];
var index = imageList.indexOf(200); // 1

You will get -1 if it cannot find a value in the array.

Find Value in Nested Array

You have to use a different method based on the value property type, if the value is an array then use Array#some method to achieve the result.

let res = fruits.find(({ value }) => Array.isArray(value) ? value.some(({ val }) => val === snacks) : value === snacks) || fruits[0]

const snacks = "strawberry";

const fruits = [{

    label: "yellowFruit",

    value: "banana"

  },

  {

    label: "purpleFruit",

    value: "grape"

  },

  {

    label: "redFruit",

    value: [{

        val: "apple"

      },

      {

        val: "strawberry"

      }

    ]

  },

  {

    label: "greenFruit",

    value: "waltermelon"

  },

];

let res = fruits.find(({ value }) => Array.isArray(value) ? value.some(({ val }) => val === snacks) : value === snacks) || fruits[0]

console.log(res);

Find value and index of Javascript array element when the index meets another condition

Another solution to this is using reduce() over the arra1:

const arr1 = [0,1,1,0,1];

const arr2 = ["a","b","c","d","e"];

let res = arr1.reduce(

    (acc, v, idx) => v ? acc.concat({val: arr2[idx], idx}) : acc,

    []

);

console.log(res);