JavaScript Array toString() Method

Array.prototype.toString() returns a string representation of an array. For normal arrays it behaves like join() with a comma separator.

const scripts = ["PHP", "ASP", "JavaScript", "HTML"];
console.log(scripts.toString());
// PHP,ASP,JavaScript,HTML

Convert an Array to a String Top ↑

const values = [10, 20, 30];
const text = values.toString();

console.log(text);        // 10,20,30
console.log(typeof text); // string

The method takes no separator argument. If you need control over the separator, use join().

Array toString() vs join() Top ↑

const values = ["A", "B", "C"];
console.log(values.toString());   // A,B,C
console.log(values.join(" - ")); // A - B - C

Array toString() uses the array's join() behavior internally in ordinary cases.

toString() with Nested Arrays Top ↑

const matrix = [[1, 2], [3, 4]];
console.log(matrix.toString()); // 1,2,3,4

The result can look flattened because nested arrays are recursively converted to comma-separated strings. Structure such as row boundaries is not preserved.

null, undefined, and Empty Slots Top ↑

const values = ["A", null, undefined, , "E"];
console.log(values.toString()); // A,,,,E

These positions become empty text between commas in the array string representation.

JavaScript May Convert Arrays to Strings Automatically Top ↑

const values = [1, 2, 3];
console.log("Values: " + values); // Values: 1,2,3
console.log(`${values}`);         // 1,2,3

Explicit conversion is usually clearer when the output format matters.

Use JSON.stringify() When You Need Structure Top ↑

const matrix = [[1, 2], [3, 4]];
console.log(matrix.toString());       // 1,2,3,4
console.log(JSON.stringify(matrix));  // [[1,2],[3,4]]

JSON.stringify() preserves JSON-compatible array/object structure, while toString() is primarily a simple textual representation.

Number toString(radix) Is a Different Method Top ↑

The original page also taught number conversion. Number.prototype.toString() can accept a radix from 2 through 36, which is different from array toString().

const value = 13;
console.log(value.toString());   // "13"
console.log(value.toString(2));  // "1101"
console.log(value.toString(8));  // "15"
console.log(value.toString(16)); // "d"

To convert strings back to integers, see parseInt().

Common toString() Mistakes Top ↑

• Passing a custom separator to array toString(); use join().
• Using array toString() as a structured serialization format.
• Confusing array toString() with number toString(radix).
• Assuming nested arrays keep their row/column boundaries in the resulting text.

Custom Separators with join() → Creating Arrays → Display Array Elements →

Subhendu Mohapatra

Author & Instructor at plus2net

I write and maintain practical tutorials on Python, PHP, SQL, JavaScript, HTML, jQuery, and web development at plus2net. The tutorials focus on clear explanations, working examples, and code that readers can test and adapt while learning.

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