What occurs when a numerical value is added to an element within an array?

Question

What occurs when a numerical value is added to an element within an array?

Illustration 1:

Let numbers = [4,5,6] + 2;

console.log(numbers) // "4,5,62"
typeof numbers // String

Illustration 2:

let nums = 10 + ["w","o","r","l","d"];

console.log(nums) // "10w,o,r,l,d";
typeof nums // String

When combining a number or string with an array using the plus operator, the result is a concatenated string where the number/string gets appended to the existing elements of the array. This might seem unusual, so let's delve into what exactly is happening in these scenarios.

javascript arrays string

Answer 1

Answer №1

When using the + operator for concatenation, it actually applies the toString() method to the array. This means that it simply joins the array elements together with commas and does not append them to the beginning or end.

The Array object overrides the toString method of Object. For Arrays, the toString method merges the elements and returns a single string with each element separated by commas.

JavaScript automatically invokes the toString method when an array needs to be displayed as text or in a string concatenation operation. (Source)

Below is a snippet demonstrating how these different approaches yield the same result:

var arr = [1, 2, 3];

// All three methods yield the same output 
// which is the result of the toString method
console.log(arr.toString())
// Concatenation with empty string at the end
console.log(arr + "")
// Concatenation with empty string at the start
console.log("" + arr);

Answer 2

When using the + operator for concatenation, it actually applies the toString() method to the array. This means that it simply joins the array elements together with commas and does not append them to the beginning or end.

The Array object overrides the toString method of Object. For Arrays, the toString method merges the elements and returns a single string with each element separated by commas.

JavaScript automatically invokes the toString method when an array needs to be displayed as text or in a string concatenation operation. (Source)

Below is a snippet demonstrating how these different approaches yield the same result:

var arr = [1, 2, 3];

// All three methods yield the same output 
// which is the result of the toString method
console.log(arr.toString())
// Concatenation with empty string at the end
console.log(arr + "")
// Concatenation with empty string at the start
console.log("" + arr);

Answer 3

Answer №2

If you want to include a new element in the array, there are several methods you can use.

As pointed out by @Pranav C Balan, the + operator is commonly used to concatenate two values in Javascript, which can sometimes be confusing. For more details on this topic, you can refer to the informative page available at JS Garden

Example 1:

Var arr = [1,2,3];
arr.push(1)


console.log(arr) // [1,2,3,1]
typeof arr // object

Example 2:

var arr = ["h","e","l","l","o"];
arr.unshift(5);

console.log(arr) // [5,"h","e","l","l","o"];
typeof arr // object

Answer 4

If you want to include a new element in the array, there are several methods you can use.

As pointed out by @Pranav C Balan, the + operator is commonly used to concatenate two values in Javascript, which can sometimes be confusing. For more details on this topic, you can refer to the informative page available at JS Garden

Example 1:

Var arr = [1,2,3];
arr.push(1)


console.log(arr) // [1,2,3,1]
typeof arr // object

Example 2:

var arr = ["h","e","l","l","o"];
arr.unshift(5);

console.log(arr) // [5,"h","e","l","l","o"];
typeof arr // object

What occurs when a numerical value is added to an element within an array?

Answer №1

Answer №2

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