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docs(blog): update every for snippets (#6650)
Co-authored-by: Batuhan Wilhelm <[email protected]>
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@@ -4,11 +4,11 @@ description: We expound with examples what the JavaScript every method is, how i | |
slug: javascript-every-method | ||
authors: abdullah_numan | ||
tags: [javascript] | ||
image: https://refine.ams3.cdn.digitaloceanspaces.com/blog/2022-11-02-js-every/social.png | ||
image: https://refine.ams3.cdn.digitaloceanspaces.com/blog/2022-11-02-js-every/social-2.png | ||
hide_table_of_contents: false | ||
--- | ||
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**_This article was last updated on February 7, 2024, to reorganize content for clarity and add new 'use cases' sections for the JavaScript 'every' method._** | ||
_**This article was last updated on January 17, 2025, to include best practices for using the JavaScript every method, a detailed table comparing every with some, and tips for avoiding common mistakes when working with sparse arrays, empty arrays, and callbacks involving thisArg.**_ | ||
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## Introduction | ||
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@@ -23,13 +23,19 @@ In this post, we expound with examples what `Array.prototype.every` is and how i | |
Steps we'll cover: | ||
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- [What is the JavaScript `Array.prototype.every` Method ?](#what-is-the-javascript-arrayprototypeevery-method-) | ||
- [JS `Array.prototype.every`: Details of the Callback Function](#js-arrayprototypeevery-details-of-the-callback-function) | ||
- [How JavaScript Array `every` Method Works](#how-javascript-array-every-method-works) | ||
- [Comparison Table: JavaScript `every` vs `some`](#comparison-table-javascript-every-vs-some) | ||
- [When to Use the JS Array `every` Method](#when-to-use-the-js-array-every-method) | ||
- [JavaScript Array `every()` With `thisArg` Argument](#javascript-array-every-with-thisarg-argument) | ||
- [JavaScript Array `every(callback, thisArg)` Doesn't Work With Arrow Functions](#javascript-array-everycallback-thisarg-doesnt-work-with-arrow-functions) | ||
- [JavaScript Array `every(callback, thisArg)` Works With Non-Arrow Functions](#javascript-array-everycallback-thisarg-works-with-non-arrow-functions) | ||
- [JavaScript Array `every` Method: Modifying the Caller Array](#javascript-array-every-method-modifying-the-caller-array) | ||
- [Nuances of Using JS Array `every` Method](#nuances-of-using-js-array-every-method) | ||
- [The JS `Array.prototype.every`: Using with Sparse Arrays](#the-js-arrayprototypeevery-using-with-sparse-arrays) | ||
- [Using JavaScript `every` With Empty Arrays](#using-javascript-every-with-empty-arrays) | ||
- [Difference Between Some and Every in JavaScript?](#difference-between-some-and-every-in-javascript) | ||
- [When Should You Use the JavaScript every Method?](#when-should-you-use-the-javascript-every-method) | ||
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## What is the JavaScript `Array.prototype.every` Method ? | ||
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In the chunk of code above, `even` is our callback function, which we pass to `every()`. Apparently, we have at least one odd number in our `numbers` array and so not all elements pass the test. So, `every()` returns `false` for `areAllEven`. In contrast, all items in `numbersDoubled` are even, so we get `true` for `areAllDoubledEven`. | ||
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## Comparison Table: JavaScript `every` vs `some` | ||
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| Feature | `every` Method | `some` Method | | ||
| ------------------ | ------------------------------------------ | ---------------------------------------------------- | | ||
| **Purpose** | Tests if **all** elements pass a condition | Tests if **at least one** element passes a condition | | ||
| **Returns** | `true` if all elements pass the test | `true` if any element passes the test | | ||
| **Stops Checking** | At the first failing element | At the first passing element | | ||
| **Empty Arrays** | Always returns `true` | Always returns `false` | | ||
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You can now directly copy and paste this table into your Markdown editor! | ||
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## When to Use the JS Array `every` Method | ||
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The JS Array `every` method can be used in a wide range of scenarios where we need to verify that all items, with no exception, satisfy the test specified in the callback function. In all cases, the first argument (`element`) has to be passed to the callback. The complexity of the test would determine whether to access the second (`index`), third arguments (`array`), or any additional argument via the `thisArg` object. | ||
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- Returns `true` only if all elements pass the test, otherwise `false`. | ||
- Stops checking once it finds a failing element. | ||
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## When Should You Use the JavaScript every Method? | ||
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### Data Validation | ||
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Use it to check if all form fields are filled in: | ||
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```javascript | ||
const fields = ["[email protected]", "password123"]; | ||
const allFieldsFilled = fields.every((field) => field.trim() !== ""); | ||
console.log(allFieldsFilled); // true if no empty fields | ||
``` | ||
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### Check Data Types | ||
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Confirm that an array contains only numbers: | ||
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```javascript | ||
const data = [1, 2, 3]; | ||
const allNumbers = data.every((item) => typeof item === "number"); | ||
console.log(allNumbers); // true | ||
``` | ||
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### Team Permissions | ||
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Verify if all team members have admin roles: | ||
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```javascript | ||
const team = [{ role: "admin" }, { role: "admin" }]; | ||
const allAdmins = team.every((member) => member.role === "admin"); | ||
console.log(allAdmins); // true | ||
``` | ||
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## FAQs About the JavaScript every Method | ||
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### 1. What is the purpose of the every method in JavaScript? | ||
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This checks whether all the elements in an array pass a test provided in a callback function. If all pass, it returns true; otherwise, false. | ||
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### 2. Does the every method work for empty arrays? | ||
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Yes, this always returns true for empty arrays since there are no elements that could fail the condition. | ||
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### 3. Can the every method modify the array? | ||
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No, the method itself doesn't change the array. However, the array can change inside the callback function. | ||
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### 4. What is the difference between every and some? | ||
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every checks if all elements meet the condition, while some checks if at least one element meets the condition. | ||
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### 5. Does the every Method Work with Objects? | ||
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Yes, but you would need to access the object properties in the callback function to test them. | ||
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## Summary | ||
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In this article, we explored in depth the **JavaScript every** which helps us test whether all items in an array pass the test we implement in a callback function. We saw with examples that the callback function can take three arguments, and additional arguments can be bound to its execution context by setting its `this` value with a `thisArg` passed to `every()` as the second argument. | ||
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