Lodash _.fill() Array Method

Posted in lodash Tutorial

Updated on Feb 18, 2024

By Mari Selvan

👁️ 36 - Views

⏳ 4 mins

💬 1 Comment

Photo Credit to CodeToFun

🙋 Introduction

Efficiently manipulating arrays is a fundamental aspect of JavaScript development. Lodash, a powerful utility library, provides a wide array of functions to simplify common programming tasks. One such versatile function is _.fill().

This method allows developers to populate specified portions of an array with a given value, offering flexibility and control over array data.

🧠 Understanding _.fill()

The _.fill() method in Lodash is designed to fill a portion of an array with a specified value. This can be particularly useful when initializing arrays, updating specific ranges, or resetting values within a given range.

💡 Syntax

syntax.js

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_.fill(array, value, [start=0], [end=array.length])

array: The array to fill.
value: The value to fill the array with.
start: The index to start filling the array (default is 0).
end: The index to stop filling the array (default is array.length).

📝 Example

Let's explore a simple example to illustrate the usage of _.fill():

example.js

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// Include Lodash library (ensure it's installed via npm)
const _ = require('lodash');

const targetArray = [1, 2, 3, 4, 5];
const filledArray = _.fill(targetArray, '*', 1, 4);

console.log(filledArray);
// Output: [1, '*', '*', '*', 5]

In this example, the filledArray is created by replacing elements from index 1 to 3 (excluding index 4) with the specified value '*' in the targetArray.

🏆 Best Practices

Validate Inputs:

Before using _.fill(), ensure that the input array is valid and contains elements. Additionally, validate the start and end indices to avoid unexpected behavior.

validate-inputs.js

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if (!Array.isArray(targetArray) || targetArray.length === 0) {
    console.error('Invalid input array');
    return;
}

const fillValue = '*';
const startIndex = 1;
const endIndex = 4;

const validatedFilledArray = _.fill(targetArray, fillValue, startIndex, endIndex);
console.log(validatedFilledArray);

Handle Edge Cases:

Consider edge cases, such as an empty array or an end index greater than the array length. Implement appropriate error handling or default behaviors to address these scenarios.

handle-edge-cases.js

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const emptyArray = [];
const invalidEndIndex = 10;

const emptyArrayFilled = _.fill(emptyArray, fillValue); // Returns: []
const invalidEndIndexFilled = _.fill(targetArray, fillValue, startIndex, invalidEndIndex); // Returns: [1, '*', '*', '*', 5]

console.log(emptyArrayFilled);
console.log(invalidEndIndexFilled);

Customize Fill Values:

Experiment with different fill values based on your specific use case. Whether it's a string, number, or complex object, _.fill() provides flexibility in customizing array content.
customize-fill-values.js
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```
const customObject = { prop: 'customValue' };
const customFilledArray = _.fill(Array(5), customObject);

console.log(customFilledArray);
```

📚 Use Cases

Initialization:

_.fill() is handy for initializing arrays with default values, creating a consistent starting point for further operations.
initialization.js
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```
const initializedArray = _.fill(Array(5), 0);

console.log(initializedArray);
// Output: [0, 0, 0, 0, 0]
```

Resetting Values:

Reset specific values in an array without modifying the rest. This is useful for implementing undo functionalities or dynamic data updates.

resetting-values.js

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const dataToReset = [10, 20, 30, 40, 50];
const resetIndices = [1, 3];
const resetValue = 0;

const resetData = _.fill(dataToReset, resetValue, ...resetIndices);

console.log(resetData);
// Output: [10, 0, 30, 0, 50]

Pattern Generation:

Create arrays with specific patterns or repetitions using _.fill().

pattern-generation.js

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const repeatingPattern = _.fill(Array(5), 'ABC');

console.log(repeatingPattern);
// Output: ['ABC', 'ABC', 'ABC', 'ABC', 'ABC']

🎉 Conclusion

The _.fill() method in Lodash empowers JavaScript developers to efficiently manipulate array data by providing a concise and flexible way to fill specific ranges with desired values. Whether initializing arrays, resetting values, or generating patterns, _.fill() is a valuable tool in your programming toolkit.

Explore the capabilities of _.fill() and elevate your array manipulation skills with Lodash!