Javascript Practice and Big Idea 1 'Program Purpose'
Learning and practicing with Javscript.
- Dynamic or Loosely typed language (string, number)
- Building a Person Function/Class object and JSON
- Making the Classroom
- Making a Table :D
- Big Idea 1 'Program and Purpose'
var msg = "Test practice variables and a message!";
console.log(msg);
Dynamic or Loosely typed language (string, number)
JavaScript is a loosely typed language, meaning you don't have to specify what type of information will be stored in a variable in advance. The variable type is determined at runtime. This is similar to Python and most interpretive languages. Java which is a compiled language is strongly typed, thus you will see string, integer, double, and object in the source code. In JavaScript, the "typeof" keyword returns the type.
function logItType(output) {
console.log(typeof output, ";", output);
}
console.log("WEEEEEEEEEEEEEEEEEEE")
logItType("Hello Mr. Yeung!"); // String
logItType(2022); // Number
logItType([1, 2, 3]); // Object is generic for this Array, which similar to Python List
// define a function to hold data for a Person
function Person(name, ghID, classOf) {
this.name = name;
this.ghID = ghID;
this.classOf = classOf;
this.role = "";
}
// define a setter for role in Person data
Person.prototype.setRole = function(role) {
this.role = role;
}
// define a JSON conversion "method" associated with Person
Person.prototype.toJSON = function() {
const obj = {name: this.name, ghID: this.ghID, classOf: this.classOf, role: this.role};
const json = JSON.stringify(obj);
return json;
}
// make a new Person and assign to variable teacher
var teacher = new Person("Mr Yeung", "Syeung2", 2013);
teacher.setRole("Coolest Teacher :)");
// output of Object and JSON/string associated with Teacher
logItType(teacher); // object type is easy to work with in JavaScript
logItType(teacher.toJSON()); // json/string is useful when passing data on internet
// define a student Array of Person(s)
var students = [
new Person("Naja", "NajaAFonseca", 2025),
new Person("Lydia", "lydia-c2", 2024),
new Person("Lina", "linaawad1", 2024),
new Person("Dylan", "DylanGarrett", 2025),
];
// define a classroom and build Classroom objects and json
function Classroom(teacher, students){ // 1 teacher, many student
// start Classroom with Teacher
teacher.setRole("Teacher");
this.teacher = teacher;
this.classroom = [teacher];
// add each Student to Classroom
this.students = students;
this.students.forEach(student => { student.setRole("Student"); this.classroom.push(student); });
// build json/string format of Classroom
this.json = [];
this.classroom.forEach(person => this.json.push(person.toJSON()));
}
// make a CompSci classroom from formerly defined teacher and students
compsci = new Classroom(teacher, students);
// output of Objects and JSON in CompSci classroom
logItType(compsci.classroom); // constructed classroom object
logItType(compsci.classroom[0].name); // abstract 1st objects name
logItType(compsci.json[0]); // show json conversion of 1st object to string
logItType(JSON.parse(compsci.json[0])); // show JSON.parse inverse of JSON.stringify
// define an HTML conversion "method" associated with Classroom
Classroom.prototype._toHtml = function() {
// HTML Style is build using inline structure
var style = (
"display:inline-block;" +
"background:black;" +
"border: 2px solid grey;" +
"box-shadow: 0.8em 0.4em 0.4em grey;"
);
// HTML Body of Table is build as a series of concatenations (+=)
var body = "";
// Heading for Array Columns
body += "<tr>";
body += "<th><mark>" + "Name" + "</mark></th>";
body += "<th><mark>" + "GitHub ID" + "</mark></th>";
body += "<th><mark>" + "Class Of" + "</mark></th>";
body += "<th><mark>" + "Role" + "</mark></th>";
body += "</tr>";
// Data of Array, iterate through each row of compsci.classroom
for (var row of compsci.classroom) {
// tr for each row, a new line
body += "<tr>";
// td for each column of data
body += "<td>" + row.name + "</td>";
body += "<td>" + row.ghID + "</td>";
body += "<td>" + row.classOf + "</td>";
body += "<td>" + row.role + "</td>";
// tr to end line
body += "<tr>";
}
// Build and HTML fragment of div, table, table body
return (
"<div style='" + style + "'>" +
"<table>" +
body +
"</table>" +
"</div>"
);
};
// IJavaScript HTML processor receive parameter of defined HTML fragment
$$.html(compsci._toHtml());