Let me know if you have any feedback using this. This post is mainly to show the dynamism of both Object keys and values. This illustration also shows the use of conditions in the form of ternary operators. It looks like this: const dataFromAPI = 'age' let existingObject = Recently, I found a 'funny' JS syntax when reviewing a pull request by Sigo, a colleague. I searched for a stock image on unsplash for "Puppies with different colors being named by their mom". Special keywords oftentimes are displayed with a different color in your IDE and even in the console of the developer tools of some browsers like in the example below.Excuse the barrage of doggos in the banner image. However, you should remember true, false, null, and undefined are valid identifiers, even though they are special keywords in JavaScript. In this case, we didn’t see any errors as when we were using a numeric property key when using the Dot property accessor. square brackets or Dot property acccessors El método Object.keys() devuelve un array de las propiedades names de un objeto, en el mismo orden como se obtienen en un loop normal Sintaxis Object. it will succeed displaying all the object properties when using The Object. Here is a ES5 functional method of sorting.
This example list the enumerable properties of an object.
Let’s not forget other object types in JavaScript such as Boolean, Null, and Undefined. In this case, we know any value within double or single quotes is a string. Looks in reality more like the following behind the scenes:Ĭonsole.log(test) // it also displays "Number One" Here is the thing, JavaScript parses the key used inside when using the square brackets property accessor. Why Did it Work Using Square Brackets Property Accessor? Var = test // it will succeedĬonsole.log(test.number) // it displays "Number One"Īha! We are getting some errors using Dot property accessor and Object Destructuring (unless you define a proper identifier name when destructuring the object). If you’re okay with mutating data, renaming an object’s key.
Edit: See how to rename many object keys here. First attempt using object destructuring Immutably Rename Object Keys in Javascript. Attempt using the Dot property accessor The JavaScript keys() method does not ignore the hole present in an array if we need to ignore holes we can use the object.keys() method. Try using the Dot property accessor and Object Destructuring to log the 1 property of our test object. There are other ways to access property values in JavaScript: Accessing Values Using Dot Property Accessor or Assigning Values Using Object Destructuring
In fact, if you use your favorite browser’s developer tools and try running your experiments there, it will give you the initial impression you can add numbers for an object key.Īccessing Values Using the Square Brackets Property Accessorĭepending on the way you decide to access the object’s numeric key-value, you will find success.Ĭonsole.log(test) // it displays "Number One"ĭon’t let the programming language fool you. If you tried the following, you noticed you didn’t get any errors.
Let’s go ahead and try creating the following object :
That’s why I validate my point by running a series of quick experiments with JavaScript Experimenting Object Keys in JavaScriptīased on my definition, I shouldn’t be able to define a key using a data type different from strings. Object keys can only be strings, and even though a developer can use other data types to set an object key, JavaScript automatically converts keys to a string a value.Īs good engineers, developers, programmers, or enthusiasts, you should strive to not naively believe this, but instead, test the language.
For those who have worked with JavaScript for a while, you will understand there are certain behaviors about the language that makes it seem it works in a certain way, when in reality it doesn’t, such as using = and = equals to check for equality between two different values.Īgainst what many think, JavaScript object keys cannot be Number, Boolean, Null, or Undefined type values.