The prompt() method
This program prompts “What is your name?” The result of the prompting is stored in the variable “myname” which is then used to write to the page. If we entered “Kodeclik” we will obtain:
The prompt() method with two arguments
In the above program if you just clicked on “OK” without entering any input, you will get:
Similarly, if you pressed on “Cancel” at the prompt, you will get:
We can update the statement with the prompt() method to provide a default value:
This will display “Harry Potter” as the default value in the prompt so if the user just presses OK without changing anything, we will get:
(If the user presses Cancel, you will still get “null”).
If you would like to ensure that the value is not a “null” by the user hitting Cancel, and also trap the case where the user enters an empty string (covered above), you can try something like:
Here, the prompt box will be adamant and refuse to accept either an empty input or a “cancel” input. You will have to enter some text and only then exit the do..while loop at which point the name you entered will be printed in the HTML page.
Getting user input via a textbox
The second way to obtain user input is via a form with textboxes. In the code below, we are using a form to obtain two numbers as input from the user and then we will print their sum. We set up two textfields with names that we can refer to the underlying elements.
First, we setup a form with two input text fields with ids “number1” and “number2”. When we click the Submit button the adder() function is invoked. Inside the adder() function, we retrieve the elements (specifically, their values). Then we add them (taking care to parse them as integers) and print the sum.
The main form looks like (with sample inputs of 23 and 46):
Kodeclik is an online coding academy for kids and teens to learn real world programming. Kids are introduced to coding in a fun and exciting way and are challeged to higher levels with engaging, high quality content.