how to name a javascript variable

1	//variables can include any letter, any number, or the underscore
2	//NO SPACES!!! USE UNDERSCORES!!!
3	//variable names are case sensitive
4	//example:
5var change_this = 'whatever you want here'
6	//change_this is a variable (change it to your variable name)
7	//'whatever you want here' is a string (you'll learn about this later)
8	

1var a = [1, 3, 4, 3]
2var b = [1, 5, 6, 7]
3var c = [3, 4, 8, 9]
4
5function arraySum(x, varName) {
6    var sum = 0
7    for (let i = 0; i < x.length; i++) {
8        sum += x[i]
9    }
10    console.log("sum of " + varName + " is " + sum)
11}
12
13arraySum(a, "a");