Lodash _.overEvery() Method

Syntax, Parameter and Return Value

Syntax:

 _.overEvery([predicates=[_.identity]])

Parameters:

[predicates=[_.identity]] (...(Function|Function[])): The functions to check.

Return Value:

 (Function) - Returns the new composite function.

Examples 

Combining Multiple Validation Checks:

• JavaScript

JavaScript

var _ = require('lodash');

var isEven = n => n % 2 === 0;

var isPositive = n => n > 0;

var isValidNumber = _.overEvery([isEven, isPositive]);

console.log(isValidNumber(4));

console.log(isValidNumber(-2));

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Output: 

true (even and positive)
false (even but not positive)

Demonstrates using _.overEvery() to create a function that checks if a number is both even and positive.

Validating Complex Conditions:

• JavaScript

JavaScript

var hasValidLength = arr => arr.length > 2;

var allNumbers = arr => _.every(arr, _.isNumber);

var isArrayValid = _.overEvery([hasValidLength, allNumbers]);

console.log(isArrayValid([1, 2, 3])); 

console.log(isArrayValid([1, 'a', true]));

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Output: 

true (valid length and all numbers)
false (not all numbers)

Shows how to validate an array based on length and content type.

Using with Object Properties:

• JavaScript

JavaScript

var isActive = obj => obj.active;

var isAdult = obj => obj.age >= 18;

var canParticipate = _.overEvery([isActive, isAdult]);

console.log(canParticipate({ age: 20, active: true }));

console.log(canParticipate({ age: 17, active: true }));

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Output: 

true
false

An example of using _.overEvery() to check if an object represents an active adult.

Filtering Based on Multiple Criteria:

• JavaScript

JavaScript

var products = [

  { name: 'Apple', category: 'fruit', stock: 10 },

  { name: 'Carrot', category: 'vegetable', stock: 0 }

];

var isFruit = product => product.category === 'fruit';

var isInStock = product => product.stock > 0;

var availableFruits = _.filter(products, _.overEvery([isFruit, isInStock]));

console.log(availableFruits);

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Output:

 [{ name: 'Apple', category: 'fruit', stock: 10 }]

Demonstrates filtering a collection based on multiple conditions using _.overEvery().

Frequently Asked Questions

How does _.overEvery() differ from _.overSome()?

_.overEvery() checks that all predicates return truthy (like logical AND), whereas _.overSome() checks if any of the predicates return truthy (like logical OR).

Can _.overEvery() handle asynchronous predicates?

_.overEvery() is designed for synchronous predicate functions. Asynchronous predicates would require handling with Promises or async/await.

Is _.overEvery() efficient for a large number of predicates?

The efficiency of _.overEvery() depends on the complexity and performance of the individual predicates. For a large number of computationally intensive predicates, performance considerations may be necessary.

Conclusion

Lodash's _.overEvery() method is an effective tool for combining multiple predicate functions into a single function that checks if all conditions are met. It simplifies complex validation logic and is useful in a variety of scenarios, from data validation to conditional rendering in applications.

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