--description--

Let’s meet the features of JavaScript operators that are beyond school arithmetics.

Usually, the plus operator + sums numbers.

But, if the binary + is applied to strings, it merges (concatenates) them:

let s = "my" + "string";
console.log(s); // mystring

Note that if any of the operands is a string, then the other one is converted to a string too.

For example:

console.log(1 + '2'); // '12'
console.log('1' + 2); // '12'

See, it doesn’t matter whether the first operand is a string or the second one.

Here’s a more complex example:

console.log(2 + 2 + '1') // "41" and not "221"

Here, operators work one after another. The first + sums two numbers, so it returns 4, then the next + adds the string 1 to it, so it’s like 4 + '1' = '41'.

console.log('1' + 2 + 2) // "122" and not "14"

Here, the first + concatenates the string and the number, so it returns '12', then the next + adds 2 to it, so it’s like '12' + 2 = '122'.

The binary + is the only operator that supports strings in such a way. Other arithmetic operators work only with numbers and always convert their operands to numbers.

Here’s the demo for subtraction and division:

console.log( 6 - '2' ); // 4, converts '2' to a number
console.log( '6' / '2' ); // 3, converts both operands to numbers

--questions--

--text--

Considering the behavior of the + operator with mixed data types in JavaScript, what will be the output of the following code snippet?

console.log('3' + 2 - 1);

--answers--

31, because the + operator concatenates the string and number before subtraction.

32, because + concatenates the string and number before subtraction.

4, because all operands are converted to numbers first.

321, because the - operator is not supported with strings.

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