Shortcut in JavaScript for verifying a specific key-value within an array of objects

Question

Shortcut in JavaScript for verifying a specific key-value within an array of objects

As an angular developer, I have limited knowledge of JavaScript shorthand methods.

I recently encountered a situation where I needed to loop through an array using a for loop in JavaScript.

Let's say I have an array of Objects like:

var arr = [{name:'abc', val:1}, {name:'xyz', val:2}, ....];

If given a string 'xyz', is there a more concise way in JavaScript or Angular to determine if my array of objects contains an object with the name 'xyz' without using a for loop?

I am hoping for a shorthand expression similar to the indexOf function.

Any assistance would be greatly valued.

javascript angularjs shorthand

Answer 1

Answer №1

If you are working with pre-ES6 code, you have the option to use:

if (arr.filter(function(x) { return x.name === 'xyz'; }).length > 0) { ... }

This method may seem a bit cumbersome, but you can make it more readable and flexible by creating a separate function like this:

function equaling(attr, value) { 
  return function(obj) {
    return (obj || {})[attr] === value; 
  };
}

if (arr.filter(equaling('name', 'xyz')).length > 0) { ... }

For those using ES6 / ES2015, a more concise way of achieving the same result is:

if (arr.some(({ name }) => name === 'xyz')) { ... }

By taking advantage of the latest language features, like arrow functions and object spread expressions, your code becomes more readable, expressive, and maintainable without the need for custom functions.

The key features include:

(value) => expression: Arrow functions provide a shorthand way of defining functions, closely resembling ES5 function definitions but with different behavior for this.
({ name }) => ...: Object spread expressions allow easy de-structuring of objects based on attribute names.

Answer 2

If you are working with pre-ES6 code, you have the option to use:

if (arr.filter(function(x) { return x.name === 'xyz'; }).length > 0) { ... }

This method may seem a bit cumbersome, but you can make it more readable and flexible by creating a separate function like this:

function equaling(attr, value) { 
  return function(obj) {
    return (obj || {})[attr] === value; 
  };
}

if (arr.filter(equaling('name', 'xyz')).length > 0) { ... }

For those using ES6 / ES2015, a more concise way of achieving the same result is:

if (arr.some(({ name }) => name === 'xyz')) { ... }

By taking advantage of the latest language features, like arrow functions and object spread expressions, your code becomes more readable, expressive, and maintainable without the need for custom functions.

The key features include:

(value) => expression: Arrow functions provide a shorthand way of defining functions, closely resembling ES5 function definitions but with different behavior for this.
({ name }) => ...: Object spread expressions allow easy de-structuring of objects based on attribute names.

Answer 3

Answer №2

To avoid using quick shorthand, the most concise and efficient approach would be to utilize Array.some

var hasName = arr.some(o => o.name === "xyz")

This method will stop as soon as a matching element is found and will return either true or false

Answer 4

To avoid using quick shorthand, the most concise and efficient approach would be to utilize Array.some

var hasName = arr.some(o => o.name === "xyz")

This method will stop as soon as a matching element is found and will return either true or false

Answer 5

Answer №3

To find what you're looking for, use the angular forEach function to iterate through and search.

let indexFound = -1;
angular.forEach($scope.list, (element, elementIndex) => {
   if(element.label === "abc"){
      indexFound = elementIndex;
   }
});
console.log(indexFound);

Answer 6

To find what you're looking for, use the angular forEach function to iterate through and search.

let indexFound = -1;
angular.forEach($scope.list, (element, elementIndex) => {
   if(element.label === "abc"){
      indexFound = elementIndex;
   }
});
console.log(indexFound);

Answer 7

Answer №4

If you're unable to utilize the "some" function on an array, a simple solution would be to create a straightforward for loop and perform your testing inside of it.

Avoid relying on array functions like "forEach" or "filter," as they will necessitate examining the entire array every time, resulting in worst-case performance, even when the desired item is at the beginning of the array. Attempting to short-circuit "forEach" or "filter" can lead to messy solutions such as wrapping the function call in a try-catch block and triggering an exception once a match is found (which is not recommended).

Therefore, if using the "some" function is off-limits, opt for a basic for loop instead and break out of it as soon as you discover a match.

Answer 8

If you're unable to utilize the "some" function on an array, a simple solution would be to create a straightforward for loop and perform your testing inside of it.

Avoid relying on array functions like "forEach" or "filter," as they will necessitate examining the entire array every time, resulting in worst-case performance, even when the desired item is at the beginning of the array. Attempting to short-circuit "forEach" or "filter" can lead to messy solutions such as wrapping the function call in a try-catch block and triggering an exception once a match is found (which is not recommended).

Therefore, if using the "some" function is off-limits, opt for a basic for loop instead and break out of it as soon as you discover a match.

Answer 9

Answer №5

To tackle this issue, consider implementing array.findIndex. You can generate a function that verifies the presence of an element with a specific name:

const findByName = (name) => arr.findIndex(elem => elem.name === 'xyz') > -1;

Subsequently, apply it like so:

findByName('xyz')  // true
findByName('differentName')  // false

See it in action: https://example.com/12345

Answer 10

To tackle this issue, consider implementing array.findIndex. You can generate a function that verifies the presence of an element with a specific name:

const findByName = (name) => arr.findIndex(elem => elem.name === 'xyz') > -1;

Subsequently, apply it like so:

findByName('xyz')  // true
findByName('differentName')  // false

See it in action: https://example.com/12345

Shortcut in JavaScript for verifying a specific key-value within an array of objects

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

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