When using the JavaScript .sort() method, any undefined value must always be considered as coming before any other value

Question

When using the JavaScript .sort() method, any undefined value must always be considered as coming before any other value

I am working on sorting an array of objects based on multiple fields, typically around 3-4 fields. Some values within the objects may be undefined, and I need to ensure that these undefined values are considered as "earlier" in the sorting process, whether it is ascending or descending order. Currently, my code works well for descending sorting, but when it comes to ascending sorting, the undefined values end up at the bottom instead of at the top. These undefined values are always strings, and I am only able to use the .sort() method without any additional operations before or after it. Here is a snippet of my code:

[{id: "1", label: "Z", code: "Z"}, 
 {id: "1", code: "A"},
 {id: "2", label: "A",},
 {id: "3", label: "A", code: "A"}]
     .sort((a,b) => {
          return a.id.localeCompare(b.id)
             || a.label.localeCompare(b.label)
             || a.code.localeCompare(b.code)
     );

javascript sorting

Answer 1

Answer №1

Creating your custom comparison function is the key here. If the result is 0, it means they are the same; a positive number suggests that b should be placed before a; and a negative number indicates that a should come first.

const localeCompareUndefined = (a, b, locales, options) => {
  if (a === undefined && b === undefined) return 0;
  else if (b === undefined) return 1;
  else if (a === undefined) return -1;
  else return a.localeCompare(b, locales, options);
}

const data = [{id: "1", label: "Z", code: "Z"}, 
 {id: "1", code: "A"},
 {id: "2", label: "A",},
 {id: "3", label: "A", code: "A"}]
.sort((a, b) => {
  return localeCompareUndefined(a.id, b.id) ||
    localeCompareUndefined(a.label, b.label) ||
    localeCompareUndefined(a.code, b.code)
});

console.log(data);

Answer 2

Creating your custom comparison function is the key here. If the result is 0, it means they are the same; a positive number suggests that b should be placed before a; and a negative number indicates that a should come first.

const localeCompareUndefined = (a, b, locales, options) => {
  if (a === undefined && b === undefined) return 0;
  else if (b === undefined) return 1;
  else if (a === undefined) return -1;
  else return a.localeCompare(b, locales, options);
}

const data = [{id: "1", label: "Z", code: "Z"}, 
 {id: "1", code: "A"},
 {id: "2", label: "A",},
 {id: "3", label: "A", code: "A"}]
.sort((a, b) => {
  return localeCompareUndefined(a.id, b.id) ||
    localeCompareUndefined(a.label, b.label) ||
    localeCompareUndefined(a.code, b.code)
});

console.log(data);

When using the JavaScript .sort() method, any undefined value must always be considered as coming before any other value

Answer №1

Similar questions

retrieve the value of a specific key using JSON stringify

Mastering the art of utilizing sequelize and promises effectively

What causes an ajax request to submit "none" as the value of a dom element?

Utilize Angular to inject an input from a component directly into the header of my application

Using Reactjs to automatically populate text into a React-Select Input field

Executing JavaScript - Triggering an 'onClick' event within a For loop to dynamically load multiple hyperlinks

What is the most efficient approach to save a value for future utilization in a subsequent function? I've heard that exploiting global variables is highly unfavorable

Changing Table Cell Color with Bootstrap Based on Value

Line of cubes - tap on a single cube and the others gracefully slide away from view

Issue with conflicting trigger events for clicking and watching sequences in input text boxes and checkboxes within an AngularJS application

Using Kendo TabStrip to dynamically include HTML files as tabs

Best practices for server side countdown implementation

Exploring the capabilities of VueJs in detecting events triggered by parent components

Uppercase the initial letter in a term to indicate a standard condition

Can Express POST / GET handlers accommodate the use of jQuery?

Developing an Easy-to-Use PDF Popup Interface

What is the best way to incorporate a dropdown header in Material-UI on a React project?

Nuxt: Delaying Loading of Google Maps in VueJS Until Data is Fully Prepared

Is it possible to trim a video using HTML code?

"Jquery's .append function may sometimes display as undefined when