Comparing an Array and a String Using == in JavaScript – Asked in an HCL Tech Interview.

Understanding the Code Step by Step

The given JavaScript snippet involves a comparison (==) between an array (x) and a string (y). Let’s break it down carefully to understand the output.

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Step 1: Understanding the Given Code

const x = [1, 2];
const y = '1,2';
console.log(x == y);

Here:

• x is an array containing two elements: [1, 2]
• y is a string: "1,2"

The key operation in this code is:

x == y

This involves type coercion because the == (loose equality) operator performs implicit conversions when comparing different data types.

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Step 2: How Does JavaScript Handle == Between an Array and a String?

In JavaScript, when an array is compared with a string using ==, the array is first converted into a primitive value (typically a string) before the comparison.

👉 Rule: When an array is used in a non-numeric context, JavaScript automatically calls its .toString() method.

How x (the array) is converted to a string?

x.toString(); // "1,2"

The toString() method for an array joins its elements with a comma (","), producing:

"1,2"

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Step 3: Evaluating the Comparison

Now, our expression:

x == y

becomes:

"1,2" == "1,2"

Since both values are now strings and they are exactly the same, the comparison evaluates to:

true

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Step 4: Logging the Output

console.log(x == y);

Console Output:

true

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🔍 Key Takeaways

1. Array to String Conversion: When an array is compared to a string, JavaScript first converts the array to a string using its toString() method.
2. Type Coercion in ==: The loose equality operator (==) allows implicit type conversion, leading to unexpected results if not understood properly.
3. Best Practice: To avoid unexpected type coercion, always use strict equality (===), which does not perform implicit conversions.

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✔ Final Answer:

A) true

🔹 This question appeared in the HCL Tech 2nd round of interview, testing the candidate’s knowledge of type coercion and the comparison (==) operator in JavaScript.