Unexpected Array Concatenation in JavaScript: Why is [1,2] [3,4] = "1,23,4"?

In JavaScript, attempting to add the elements of two arrays using the operator, as in the expression [1,2] [3,4], yields an unexpected result of "1,23,4" instead of [1,2,3,4]. This behavior is due to the following reasons:

1. Array Conversion: JavaScript does not have a native ' ' operator for arrays. Instead, it implicitly converts arrays into strings using the toString() method.

2. String Concatenation: The ' ' operator in JavaScript performs string concatenation. When arrays are converted into strings, they are represented as comma-separated lists of their elements.

3. Unexpected Result: Therefore, the expression [1,2] [3,4] is essentially equivalent to "1,2" "3,4," which results in the concatenated string "1,23,4."

Additional Note:

While arrays lack a ' ' operator, there are several methods specifically designed for array manipulation:

• concat(): Concatenates two or more arrays into a new array.
• push(): Adds one or more elements to the end of an array.
• unshift(): Adds one or more elements to the beginning of an array.

To avoid unexpected behavior like the one described above, it's advisable to use these methods when working with arrays.