Read: 07 - Programming with Javascript

**reminder to self: there are some aspects of JS that are similar to python. Example, declaring functions, if, then, else statements, operators (most mathematical operators carry over +, *, /, -, **… etc)

A javascript function must first be declared, named and then given parameters of what it should execute when called on (invoked)

Functions are used to “declare” a named set of instructions for javascript to execute when the declared function is called (invoked)

The name of a function should follow camel case if using more than one word to name the function. So if you wanted to name a function for “changing font type” you could enter changeFontType to conform with camel case rather than ChangeFontType or changefonttype

The optional parameters inclosed with () after the function name can give your function a parameter to run against the function code. You can have multiple parameters within the () as long as they are separated by a , example: (red, green, blue)

Example of a Javascript function with variables:

    function multiplyNumbers(price, shipping) {
    //Return the sum
        return price*shipping;
    }

    //Call MULTIPLY to multiply the two numbers
    var product=multiplyNumbers(22, 2);

    console.log(product)

This example has a function named multiplyNumbers. This function contains the parameters (price, shipping) and it ends with a {

Next we add the code we want the function to execute. For this example we want the code to return price*shipping; this will return the value of price multiplied by shipping. This function is then closed with } following the code that the function will execute.

Below the function we have a variable that names “product” being equal to our function with the numbers (22, 2) Theses numbers will replace the parameters in our named function and will return the sum of 22*2 when we write to the console with console.log(product) Javascript can be linked in the head of your html document with

And then a function within your javascript file such as:

    function likeCardio(){  
        let usersChoice = prompt("do you like cardio?");
   
        if (usersChoice.toLowerCase() == "yes"){
            document.write("so you like cardio? perfect, let's train");
    } else{
        document.write("not a fan of cardio? that's alright, feel free to look around and maybe check out strength");
    }
}

Can be called (invoked) with a script in your HTML file where you want the code to display in your HTML page such as:

    <script>likeCardio();</script>