If/else

if.js

if (something === something) {
    if (somethingelse === somethingelse) {
       // somethingelse equals somethingelse
    } else {
       // somethingelse isn't equal to somethingelse
    }
} else {
  // something doesn't equal something
}

// What you had was...

if (a === b) {
  // do something
} 

if (c === d) {
  // do something else
}

// in that case, two separate things will happen



// This is what you originally had


var compare = function(choice1, choice2) { 
    if (choice1 === choice2) {
        return("The result is a tie!"); 
    }

    if (choice1 === "rock") {
        if (choice2 === "scissors") {
            return("Rock wins!");
        } else {
            return("Paper wins!");
        }
    }

// Now we have

var compare = function(choice1, choice2) { 
    if (choice1 === choice2) {
        return("The result is a tie!");
    } else if (choice1 === "rock") {
        if (choice2 === "scissors") {
            return("Rock wins!");
        } else {
            return("Paper wins!");
        } 
    }

Now we are here:

var compare = function(choice1, choice2)
{ if (choice1 === choice2) {
    return("The result is a tie!"); }
else if (choice1 === "rock") {
    if (choice2 === "scissors") {
        return("Rock wins!");}
    else {
        return("Paper wins!");} 
}

Here we go! (I think...)

var compare = function(choice1, choice2)
    { if (choice1 === choice2) {
        return("The result is a tie!"); 
    } else if (choice1 === "rock")
        if (choice2 === "scissors") {
            return("Rock wins!");
        } else {
            return("Paper wins!");
        } 
    };

And again, with more...

var compare = function(choice1, choice2)   
{ if (choice1 === choice2) {
    return("The result is a tie!"); 
} else if (choice1 === "rock") {
    if (choice2 === "scissors") {
        return("Rock wins!");
    } else {
        return("Paper wins!");
    }
} else if (choice1 === "paper") {
        if (choice2 ==="rock") {
            return("Paper wins!");
    } else {
        return("Scissors wins!");
    }
} else if (choice1 === "scissors") {
        if (choice2 === "rock") {
            return("Rock wins!");
        } else {
            return("Scissors wins!");
    }
};

Let's clean it up a bit

var compare = function(choice1, choice2)   { 
    if (choice1 === choice2)  {
        return("The result is a tie!"); 
    } else if (choice1 === "rock")  {
        if (choice2 === "scissors")  {
            return("Rock wins!");
        } else {
            return("Paper wins!");
        }
    } else if (choice1 === "paper")  {
        if (choice2 ==="rock")  {
            return("Paper wins!");
        } else {
            return("Scissors wins!");
        }
    } else if (choice1 === "scissors")  {
        if (choice2 === "rock") {
            return("Rock wins!");
        } else {
            return("Scissors wins!");
        }
    };