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Thread: New to JS. Very new. Need some help with this simple script.

  1. #1
    Join Date
    Apr 2012
    Posts
    14

    New to JS. Very new. Need some help with this simple script.

    I am taking a class right now and I want to learn JavaScript because I would love to do this as a career in the future.
    The assignment is to Create a Web page that allows a user to enter a purchase price into a text box; include a JavaScript function that calculates
    shipping and handling. Add functionality to the script that adds a
    minimum shipping and handling fee of $1.50 for any purchase that is
    less than or equal to $25.00. For any orders over $25.00, add 10% to
    the total purchase price for shipping and handling, but do not include
    the $1.50 minimum shipping and handling fee. Th e formula for calculating
    a percentage is price * percent / 100. For example, the formula
    for calculating 10% of a $50.00 purchase price is 50 * 10 / 100, which
    results in a shipping and handling fee of $5.00. After you determine
    the total cost of the order (purchase plus shipping and handling),
    display it in an alert dialog box.

    Here is what I came up with:

    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"

    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

    <html xmlns="http://www.w3.org/1999/xhtml">

    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <link rel="stylesheet" href="js_styles.css" type="text/css" />

    <title>Week 2 Calculating The Shipping Fees</title>

    <script type="text/javascript">
    /* <![CDATA[ */

    function calcShipping();
    {
    if (price <= 25);
    shipping = 1.50 ;
    shipping = (price *(10/100);
    }
    /* ]]> */
    </script>
    </head>

    <body>

    <script type="text/javascript">
    /* <![CDATA[ */

    document.write("Purchase price and shipping total");
    /* ]]> */
    </script>

    <script type="text/javascript">
    /* <![CDATA[ */
    var price=prompt("What is the purchase price?");

    function calcShipping();
    document.write ("The purchase price is $" " + (price) + ");
    document.write ("The cost of shipping is $" " + (shipping) + ");

    var total = price + shipping;
    document.write("Your total price with shipping is $ " + (total) + ");
    /* ]]> */
    </script>

    </body>
    </html>

  2. #2
    Join Date
    Apr 2012
    Posts
    14
    I am having trouble figuring out how to add the text box and link that to the JavaScript.

  3. #3
    Join Date
    May 2006
    Location
    Somewhere behind your screen
    Posts
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    Code:
    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"  "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
    <html xmlns="http://www.w3.org/1999/xhtml">
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <link rel="stylesheet" href="js_styles.css" type="text/css" />
    <title>Week 2 Calculating The Shipping Fees</title>
    <script type="text/javascript">
    function calcShipping(){
    var price=new Number(document.getElementById('pr').value);
    if(price <=0 || price=='' || isNaN(price)==true){alert('Wrong input!');return;}
    var fee=0,total_price=0;
    if(price <= 25){fee=1.50;total_price=price+fee;}
    else{fee=price*10/100;total_price=price+fee;}
    alert('Total shipping price is '+total_price+' ('+price+' + '+fee+')');
    }
    </script>
    </head>
    <body>
    <center>
    <br /><br /><br /><br /><br /><br /><br /><br />
    <input id="pr" type="text" size="20" style="text-align:center;" value="" /><br /><br /><a href="#null" onclick="calcShipping()">calculate</a>
    </center>
    </body>
    </html>
    Last edited by Padonak; 04-01-2012 at 03:14 PM. Reason: isNaN(price)==true added

  4. #4
    Join Date
    Apr 2012
    Posts
    14
    Hello I see that you did modify the script a lot but is that advanced? I do not completely understand all of this here

    <script type="text/javascript">
    function calcShipping(){
    var price=new Number(document.getElementById('pr').value);
    if(price <=0 || price=='' || isNaN(price)==true){alert('Wrong input!');return;}
    var fee=0,total_price=0;
    if(price <= 25){fee=1.50;total_price=price+fee;}
    else{fee=price*10/100;total_price=price+fee;}
    alert('Total shipping price is '+total_price+' ('+price+' + '+fee+')');
    }

    This is a basic javascript class what is the dumbed down version of this?

  5. #5
    Join Date
    Apr 2012
    Posts
    14
    I tried to take what you had and what I had but it does not calculate.

    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"

    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

    <html xmlns="http://www.w3.org/1999/xhtml">

    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <link rel="stylesheet" href="js_styles.css" type="text/css" />

    <title>Week 2 Calculating The Shipping Fees</title>

    <script type="text/javascript">
    /* <![CDATA[ */

    function calcShipping();
    {
    if (price <= 25);
    shipping = 1.50 ;
    shipping = (price *(10/100);
    }
    /* ]]> */
    </script>
    <script type="text/javascript">
    /* <![CDATA[ */

    document.write(<p>"Purchase price and shipping total"</p>);
    /* ]]> */
    </script>

    <script type="text/javascript">
    /* <![CDATA[ */
    var price=new number(document.getelementbyid('pr').value);

    function calcShipping();
    document.write ("The purchase price is $" " + (price) + ");
    document.write ("The cost of shipping is $" " + (shipping) + ");

    var total = price + shipping;
    document.write("Your total price with shipping is $ " + (total) + ");
    /* ]]> */
    </script>
    </head>

    <body>
    <input id="pr" type="text" size="20" style="text-align:center;" value="" /><br /><br /><a

    href="#null" onclick="calcShipping()">calculate</a>


    </body>
    </html>

  6. #6
    Join Date
    May 2006
    Location
    Somewhere behind your screen
    Posts
    1,674
    ok let's see what is wrong with your code:

    Code:
    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" 
    
     "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
    
     <html xmlns="http://www.w3.org/1999/xhtml">
    
     <head>
     <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
     <link rel="stylesheet" href="js_styles.css" type="text/css" />
    
     <title>Week 2 Calculating The Shipping Fees</title>
    
     <script type="text/javascript">
     /* <![CDATA[ */
    
     function calcShipping();//this is triggering the calcShipping() function but it has not been defined yet!
     {
     if (price <= 25);// if(condition){where is what happens if condition exists?!} 
     shipping = 1.50 ;// this variable has not been defined yet so you must write var shipping here
     shipping = (price *(10/100);// if so then what for the previous shipping?!
     }
     /* ]]> */
     </script>
    <script type="text/javascript">
     /* <![CDATA[ */
    // you don't need more than one script why do you write 3?!
     document.write(<p>"Purchase price and shipping total"</p>);
     /* ]]> */
     </script>
    
     <script type="text/javascript">
     /* <![CDATA[ */
     var price=new Number(document.getelementbyid('pr').value);//we need this to prevent anything but digits in the text field (that's why we check isNaN(price) and if it is true we stop the script)
    
     function calcShipping();//here you are triggering again the function which has never been defined
     document.write ("The purchase price is $" " + (price) + ");
     document.write ("The cost of shipping is $" " + (shipping) + ");
    
     var total = price + shipping; 
     document.write("Your total price with shipping is $ " + (total) + ");
     /* ]]> */
     </script>
     </head>
    
     <body>
     <input id="pr" type="text" size="20" style="text-align:center;" value="" /><br /><br /><a 
    
     href="#null" onclick="calcShipping()">calculate</a>
    
    
     </body>
     </html>
    now let's see what's goin on in my script:

    Code:
    <script type="text/javascript">
    //here goes the calcShipping function
     function calcShipping(){
    //first we take the value of our text field and create a new Number with this value
     var price=new Number(document.getElementById('pr').value);
    //now we're going to check price and decide can we calculate anything or not
     if(price <=0 || price=='' || isNaN(price)==true){alert('Wrong input!');return;}
    //if price <= 0 we can't calculate because this is absurd - we are here to sell goods ;-))
    //if price=='' this means that the user sent us an empty textfield so we can't calculate again
    //isNaN(price)==true this means that the user sent us letters or some bull**** else and we can't calculate aswell
    // || checks these 3 conditions one by one and if the current condition is true shows alert('Wrong input!'); and stops the futher function return;
    //if everything is OK we define 2 variables fee and total_price which are numeric both
     var fee=0,total_price=0;
    //now we check if price <= 25 and if so fee=1.50;total_price=price+fee;
     if(price <= 25){fee=1.50;total_price=price+fee;}
    //if the previous check was not true and the price is above $25 we take 10% and calculate the total_price
     else{fee=price*10/100;total_price=price+fee;}
    //and finally we alert the result
     alert('Total shipping price is '+total_price+' ('+price+' + '+fee+')');
     }
    sorry i'm not that good in the English language but i hope you'll understand my comments

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