Tutorials

Lodash _.every() Collection Method

Posted in lodash Tutorial

Updated on Feb 24, 2024

By Mari Selvan

👁️ 20 - Views

⏳ 4 mins

💬 1 Comment

Photo Credit to CodeToFun

🙋 Introduction

In the vast landscape of JavaScript, effective handling of collections is fundamental to writing robust and reliable code. Lodash, a versatile utility library, offers a multitude of functions for working with collections, and among them is the _.every() method.

This method provides an elegant and concise way to check if all elements in a collection satisfy a given condition. As a result, it becomes an indispensable tool for developers striving for code clarity and efficiency.

🧠 Understanding _.every()

The _.every() method in Lodash is designed to determine whether all elements in a collection meet a specified condition. It iterates through each element in the collection and returns true if the condition is satisfied for every element, otherwise, it returns false.

💡 Syntax

syntax.js

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_.every(collection, [predicate])

collection: The collection to iterate over.
predicate (Optional): The function invoked per iteration.

📝 Example

Let's delve into a practical example to grasp the functionality of _.every():

example.js

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const _ = require('lodash');

const numbers = [2, 4, 6, 8, 10];

const allEven = _.every(numbers, num => num % 2 === 0);

console.log(allEven);
// Output: true

In this example, the _.every() method is used to check if all numbers in the numbers array are even. The result is true since every element satisfies the given condition.

🏆 Best Practices

Understand the Predicate Function:

Ensure a clear understanding of the predicate function. The predicate is crucial as it defines the condition that each element must satisfy.

example.js

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const students = [
    { name: 'Alice', grade: 90 },
    { name: 'Bob', grade: 85 },
    { name: 'Charlie', grade: 95 },
];

const allHighAchievers = _.every(students, student => student.grade >= 90);

console.log(allHighAchievers);
// Output: false

Handle Edge Cases:

Consider edge cases to handle situations where the collection is empty or the predicate function might throw errors. Implement appropriate checks and default behaviors.
example.js
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```
const emptyCollection = [];
const isEmpty = _.every(emptyCollection);

console.log(isEmpty);
// Output: true
```

Leverage Short-Circuiting:

Take advantage of the short-circuiting behavior of _.every(). As soon as a falsy value is encountered, the iteration stops, improving performance for large collections.

example.js

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const mixedNumbers = [2, 4, 6, 7, 8, 10];

const allEven = _.every(mixedNumbers, num => {
    if (num % 2 === 0) {
        return true; // Continue iteration
    } else {
        console.log(`${num} is not even.`);
        return false; // Short-circuiting
    }
});

console.log(allEven);
// Output: false

📚 Use Cases

Validation:

Use _.every() for validating whether all elements in a collection meet specific criteria, such as form input validation or configuration checks.
example.js
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```
const formFields = [/* ...array of form field values... */];
const allFieldsValid = _.every(formFields, field => isValid(field));

console.log(allFieldsValid);
```

Permission Checks:

Determine if all users in a collection have a certain level of permission by leveraging _.every().

example.js

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const users = [
    { name: 'Alice', isAdmin: true },
    { name: 'Bob', isAdmin: false },
    { name: 'Charlie', isAdmin: true },
];

const allAdmins = _.every(users, user => user.isAdmin);

console.log(allAdmins);
// Output: false

Data Consistency:

Ensure data consistency across a collection by checking if all elements adhere to a specific format or structure.

example.js

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const dataRecords = [/* ...array of data records... */];
const isConsistentFormat = _.every(dataRecords, record => hasRequiredFields(record));

console.log(isConsistentFormat);

🎉 Conclusion

The _.every() method in Lodash provides a concise and effective way to check if all elements in a collection satisfy a given condition. Whether you're performing data validation, permission checks, or ensuring data consistency, this method proves to be a valuable asset in your JavaScript toolkit.

Embrace the power of collection manipulation with _.every() and elevate your code to new levels of clarity and efficiency!