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Extra Credit - Intro to Prog

This is the Extra Credit: Write a program that loops through the numbers 1 through 100. Each number should be printed to the console, using console.log(). However, if the number is a multiple of 3, don't print the number, instead print the word "fizz". If the number is a multiple of 5, print "buzz" instead of the number. If it is a multiple of 3 and a multiple of 5, print "fizzbuzz" instead of the number.

Hint. Use loops and if/else statments. In javascript the % is the modulo, or remainder operator. a % b evaluates to the remainder of a divided by b. 11 % 3 is equal to 2.

for (var i =  1; i <=  100; i + 1) {
    if (i % 3 = 0) {
    else if (i % 5 = 0) {
    else if (i % 5 = 0, i % 3 = 0) {
    else {

All I get from the browser is, '''Uncaught ReferenceError: Invalid left-hand side in assignment '''

What am I doing wrong? Or at least what is a better way to do this?

3 Answers

First of all, your for loop doesn't increase the value of i. You have to assign the value of incremented i to i (i = i + 1). You basically have an endless loop there.

Secondly, in your if statements, you're using the assignment operator (=) instead of using one of the equality operators (== or ===).

Also, you can't list additional conditions inside an if statement with commas. You need to use logical operators, in this case the logical AND operator (&&).

That's on the side of the syntax.

As far as the logic of your code goes, the check if a number is divisible both by 3 and 5 should be the first one. Otherwise you'll end up outputting fizz for such numbers.

Also, a number that is divisible both by 3 and 5 is actually also divisible by 15, so you can reduce that to only one check.

The end result:

for (var i =  1; i <=  100; i = i + 1) { // fixing the endless loop here
    if (i % 15 === 0) { // first check if the number is divisible by 15 (both 3 and 5)
    else if (i % 3 === 0) { // use the equality (identity) operator
    else if (i % 5 === 0) { // use the equality (identity) operator
    else {

You've got a few problems.

First, to check for equality in your if statements, you want to use the javascript logical operator === rather than the assignment operator =.

Second, in your for loop you need to actually increase the value of i. You can do this with this assignment operator i += 1.

Finally, you've got both a syntax error on your second else if as well as a logic error in the placement of this condition. To fix the former, you'll want to use one of the javascript logical operators (I'm guessing either & or ||). To fix the latter, think about the order in which your if statement conditions are being asked and executed, and remember that if statements stop advancing after the first truthy expression is found (and executes the statement therein).

Hey Scott, just wondering, could you explain how i += 1 works and the difference in &&, & and ||?

Thanks guys, really appreciate it. Makes a lot of sense now. Just got onto JS yesterday, starting to learn the syntax just takes a bit of getting used to!