substring() practice






3.25. substring() practice

Let's spend a little time practicing how to use the JavaScript substring() method, using the string you saw on the last two pages.

myString
      1Jim
  Position:     0    1    2    3    myString.length4You can
use myString.length to get the length of a string, which will always be one
greater than the last position in the string.
myString.substring(1,This substring
will start at position 1, end at position 3, and not include the character at
position 3. 3);

Ji This substring started at position 1 ("J"), and went to
position (3 - 1), which is position 2 ("i").
myString.substring(2, myString.length);Since
myString.length will be 1 greater than the last position, this will always go
to the end of a string.
im

myString.substring(0,Position 0 is the first
character in the string... myString.length);...and myString.length
will always return to the end of the string.
1Jim This JavaScript would always
return the entire string.

Just Do It

You should be ready to write the rest of the JavaScript for serveDrink() on your own now. Below is part of that function's JavaScript; your job is to fill in the blanks and get things working.

You'll need to get the response from the server, then break that response into the number of the coffee maker that brewed this order and the name of the person that placed the coffee order. Next you should set the status of the coffee maker that just finished to "Idle" and let the person that ordered coffee know that his order is ready.

function serveDrink() {
  if (request.readyState == ______) {
    if (request.status == ______) {
       var response = request.responseText;
       var whichCoffeemaker = response.substring(___, ___);
       var name = response.substring(_____, ________);Here's Where
       you can put what you just learned about substring() to use.
          if (whichCoffeemaker == "1") {
          var coffeemakerStatusDiv1 =
            document.getElementById("____________________");
          replaceText(_____________________, "Idle");
        } else {
          var coffeemakerStatusDiv2 =
            document.getElementById("____________________");
          replaceText(______________________, "_______");
        }
        ________(name + ", your coffee is ready!");
      } else
        alert("Error! Request status is " + request.status);
coffee.js




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