Can someone explain to me what the plus sign is before the variables in JavaScript?

The plus(+) sign before the variables defines that the variable you are going to use is a number variable.

In the below code, there is brief description about plus sign. Following is the code −

Example

var firstValue="1000";
console.log("The data type of firstValue ="+typeof firstValues);
var secondValue=1000;
console.log("The data type of secondValue ="+typeof secondValue);
console.log("The data type of firstValue when + sign is used ="+typeof
+firstValue);
var output=+firstValue + secondValue;
console.log("Addition is="+output);

To run the above program, you need to use the following command −

node fileName.js.

Output

Here, my file name is demo149.js. This will produce the following output −

PS C:\Users\Amit\JavaScript-code> node demo149.js
The data type of firstValue =string
The data type of secondValue =number
The data type of firstValue when + sign is used =number
Addition is=2000