var books = new Array();
books[0] = "Silmarillion: ";
books[1] = "Horus Rising: ";
books[2] = "Lord of the Rings: ";
var ratings = new Array();
ratings[0] = "9 ";
ratings[1] = "8 ";
ratings[2] = "7 ";
function printBooks()
{
for(var i = 0; i < books.length; i++)
{
document.writeln(books[i] +" " + ratings[i]);
}
}
printBooks();
I have this code and it (basically) achieves what I want it to do but it's quite bad. I'd like to have it in two functions, one function (addBooks(title, rating)) to add my books and one function (printBooks()) to print them. I'd like the user to be asked to add one book, ask the rating of it and do this three times.
After this I would like it to be printed.
I've tried to do it but I don't know how to write a function that adds into the arrays. I've only figured out I should use push() but not any more.. I hope it's clear enough.
EDIT
On top of this I would also like to have a way to calculate the average score of the books added. The code I got now for this is:
function averageRating ()
{
var sum = 0;
for(var u = 0; u < ratings.length; u++)
{
sum += parseInt(ratings[u]);
}
var avg = sum/ratings.length;
document.writeln("<br>Number of books read: " + ratings.length + "<br>The average rating of the books are: " + avg);
averageRating();
The concept is you have a library with some books.
So an OOP approach may be create a class Library with some method. Like:
function Library() {
var books = [];
this.addBook = function(bookName,rate) {
books.push({name:bookName, rating:rate});
}
this.printBooks = function() {
for(var i = 0; i < books.length; i++) {
document.writeln(books[i].name +": " + books[i].rating);
}
}
}
code:
var myLibrary = new Library();
myLibrary.addBook('Silmarillion',9);
myLibrary.addBook('Horus Rising',8);
myLibrary.addBook('Lord of the Rings',7);
myLibrary.printBooks();
However, it can be improved. You can create a class Book:
function Book(name,options) {
this.name = name;
this.rating = options.rating;
}
and class Library becomes:
function Library() {
var books = [];
this.addBook = function(book) {
books.push(book);
}
this.printBooks = function() {
for(var i = 0; i < books.length; i++) {
document.writeln(books[i].name +": " + books[i].rating);
}
}
// EDIT: ADDED for new features required
this.countBook = function() {
return books.length;
}
this.calculateRatingAverage = function() {
var sum = 0;
for(var i = 0; i < books.length; i++) {
sum += books[i].rating;
}
return sum/books.length;
}
}
and its use becomes:
var myLibrary = new Library();
myLibrary.addBook(new Book('Silmarillion',{rating:9}));
myLibrary.addBook(new Book('Horus Rising',{rating:8}));
myLibrary.addBook(new Book('Lord of the Rings',{rating:7}));
myLibrary.printBooks();
document.writeln("<br>Number of books read: " + myLibrary.countBook() + "<br>The average rating of the books are: " + myLibrary.calculateRatingAverage());
So you have a solid structure that you can optimize and work on it.
Related
When a button is clicked i want the results in the array to be listed for example: John Smith 16, Jack Snow 10 etc..
I want to use a loop however the code in my loop is incorrect at the moment as when i click the button all i get is: [object Object].
Can someone provide a possible fix?
function begin() {
listresults();
();
}
var results1 = {name:"John Smith", score:16};
var results2 = {name:"Jack Sow", score:10};
var results3 = {name:"Tessa Flip", score:15};
var results = [results1, results2, results3];
function listresults() {
var text = "";
var total = 0;
var i;
for (i in results) {
text += results[i] + "<br>";
}
document.getElementById('message').innerHTML = text;
}
I would first check that the lengths of the 2 arrays are the same. Then iterate using a for loop:
final int timeLength = TIME.length;
if (timeLength != stat.size()) {
//something may not be right
}
for (int i = 0; i < timeLength; i++) {
System.out.println(time[i]+" "+stat.get(i));
}
You are pushing objects results1, results2, etc in the array 'results'.
So while iterating the array you should access the object properties as shown below:
function listresults() {
var text = "";
var total = 0;
var i;
for (i in results) {
text += results[i]['name'] + ' ' + results[i]['score'] + "<br>";
}
As you are appending objects instead of object values in the filed.
This is the proper way of accessing name and score from object which is returned when you are looping through your array of objects :
function begin() {
listresults();
();
}
var results1 = {name:"John Smith", score:16};
var results2 = {name:"Jack Sow", score:10};
var results3 = {name:"Tessa Flip", score:15};
var results = [results1, results2, results3];
function listresults() {
var text = "";
var total = 0;
for (var i=0; i < results.length; i++) {
text += results[i].name + " " + results[i].score + "<br>";
}
document.getElementById('message').innerHTML = text;
}
Here is an Jsfiddle example
Recommend you to use Array methods(map, join) instead of pure loops
function begin() {
listresults();
}
var results1 = {name:"John Smith", score:16};
var results2 = {name:"Jack Sow", score:10};
var results3 = {name:"Tessa Flip", score:15};
var results = [results1, results2, results3];
function listresults() {
document.getElementById('message').innerHTML =
results.map(function(item) {
return item.name + ' ' + item.score;
}).join('<br>');
document.getElementById('total').innerHTML =
results.map(function(item) {
return item.score;
}).reduce(function(sum, score) {
return sum + score;
}, 0);
}
<button onclick="begin()">begin</button>
<br />
<div id="message"></div>
<div>total: <span id="total">0</span></div>
Use Array.map() and Array.join()
var results1 = {name:"John Smith", score:16};
var results2 = {name:"Jack Sow", score:10};
var results3 = {name:"Tessa Flip", score:15};
var results = [results1, results2, results3];
var res = results.map(item => { return item.name+ " " +item.score });
console.log(res.join(", "));
I am trying to reference a global variable's value using my array output but I am unsure how to do that. I want to make these references outside the function as I will need to create many functions that use these variables.
Ignore the PFGetValue part, I need to use that for the program I am coding in. There will be many more dd_meg_x but this is just to show you what I'm doing. Currently, this will return the correct the text "dd_meg_x" - but I want to then reference the variable defined above. So for example, if the result in the array is dd_meg_1, I want the output to be "M Energy 16"
var dd_meg_1 = "M Energy 16";
var dd_meg_2 = "Ulra Energy";
var dd_meg_3 = "Another Option Here";
function canOrderMeg1() {
var brand = "meg";
var arrayLength = 21;
var canArray = [];
var variableName;
for (i = 0; i <= arrayLength; i++) {
variableName = ("dd_" + brand + "_" + i);
if (PFGetValue(variableName) === "Y") {
canArray.push(variableName);
}
canArray.join(", ");
}
return canArray[0];
}
function canOrderMeg2() {
var brand = "meg";
var arrayLength = 21;
var canArray = [];
var variableName;
for (i = 0; i <= arrayLength; i++) {
variableName = ("dd_" + brand + "_" + i);
if (PFGetValue(variableName) === "Y") {
canArray.push(variableName);
}
canArray.join(", ");
}
return canArray[1];
}
Try
return eval('string output code');
So this would look like
return eval(array output);
Try this:
var dd_meg_1 = "M Energy 16";
var dd_meg_2 = "Ulra Energy";
var dd_meg_3 = "Another Option Here";
function canOrderMeg1() {
return ["dd_meg_1", "dd_meg_2", "dd_meg_3"];
}
for(let i = 0; i < canOrderMeg1().length; i++){
if(typeof canOrderMeg1()[i] !== "undefined") {
console.log(window[canOrderMeg1()[i]]);
}
}
I'm writing a program in JS for checking equal angles in GeoGebra.
This is my first JS code, I used c# formerly for game programming.
The code is:
var names = ggbApplet.getAllObjectNames();
var lines = new Set();
var angles = new Set();
var groups = new Set();
for(var i=0; i<names.length; i++)
{
if(getObjectType(names[i].e)==="line")
{
lines.add(names[i]);
}
}
for(var i=0;i<lines.size;i++)
{
for(var j=0;j<i;j++)
{
var angle = new Angle(i,j);
angles.add(angle);
}
}
for(var i=0;i<angles.size;i++)
{
var thisVal = angles.get(i).value;
var placed = false;
for(var j=0;j<groups.size;j++)
{
if(groups.get(j).get(0).value===thisVal)
{
groups.get(j).add(angles.get(i));
placed = true;
}
}
if(!placed)
{
var newGroup = new Set();
newGroup.add(angles.get(i));
groups.add(newGroup);
}
}
for(var i=0;i<groups.size;i++)
{
var list="";
for(var j=0;j<groups.get(i).size;j++)
{
list = list+groups.get(i).get(j).name;
if(j != groups.get(i).size-1)
{
list = list+",";
}
}
var comm1 = "Checkbox[angle_{"+groups.get(i).get(0).value+"},{"+list+"}]";
ggbApplet.evalCommand(comm1);
var comm2 = "SetValue[angle_{"+groups.get(i).get(0).value+"}+,0]";
ggbApplet.evalCommand(comm2);
}
(function Angle (i, j)
{
this.lineA = lines.get(i);
this.lineB = lines.get(j);
this.name = "angleA_"+i+"B_"+j;
var comm3 = "angleA_"+i+"B_"+j+" = Angle["+this.lineA+","+this.lineB+"]";
ggbApplet.evalCommand(comm3);
var val = ggbApplet.getValue(this.name);
if(val>180)
{val = val-180}
this.value = val;
ggbApplet.setVisible(name,false)
});
function Set {
var elm;
this.elements=elm;
this.size=0;
}
Set.prototype.get = new function(index)
{
return this.elements[index];
}
Set.prototype.add = new function(object)
{
this.elements[this.size]=object;
this.size = this.size+1;
}
It turned out that GeoGebra does not recognize Sets so I tried to make a Set function.
Basically it collects all lines into a set, calculates the angles between them, groups them and makes checkboxes to trigger visuals.
the GeoGebra functions can be called via ggbApplet and the original Workspace commands via ggbApplet.evalCommand(String) and the Workspace commands I used are the basic Checkbox, SetValue and Angle commands.
The syntax for GeoGebra commands are:
Checkbox[ <Caption>, <List> ]
SetValue[ <Boolean|Checkbox>, <0|1> ]
Angle[ <Line>, <Line> ]
Thank you for your help!
In short, the syntax error you're running to is because of these lines of code:
function Set {
and after fixing this, new function(index) / new function(object) will also cause problems.
This isn't valid JS, you're likely looking for this:
function Set() {
this.elements = [];
this.size = 0;
}
Set.prototype.get = function(index) {
return this.elements[index];
};
Set.prototype.add = function(object) {
this.elements[this.size] = object;
this.size = this.size + 1;
};
Notice no new before each function as well.
I'm not sure what you're trying to accomplish by creating this Set object though - it looks like a wrapper for holding an array and its size, similar to how something might be implemented in C. In JavaScript, arrays can be mutated freely without worrying about memory.
Here's an untested refactor that removes the use of Set in favour of native JavaScript capabilities (mostly mutable arrays):
var names = ggbApplet.getAllObjectNames();
var lines = [];
var angles = [];
var groups = [];
for (var i = 0; i < names.length; i++) {
if (getObjectType(names[i].e) === "line") {
lines.push(names[i]);
}
}
for (var i = 0; i < lines.length; i++) {
for (var j = 0; j < i; j++) {
angles.push(new Angle(i, j));
}
}
for (var i = 0; i < angles.length; i++) {
var thisVal = angles[i].value;
var placed = false;
for (var j = 0; j < groups.length; j++) {
if (groups[j][0].value === thisVal) {
groups[j].push(angles[i]);
placed = true;
}
}
if (!placed) {
groups.push([angles[i]]);
}
}
for (var i = 0; i < groups.length; i++) {
var list = "";
for (var j = 0; j < groups[i].length; j++) {
list += groups[i][j].name;
if (j != groups[i].length - 1) {
list += ",";
}
}
var comm1 = "Checkbox[angle_{" + groups[i][0].value + "},{" + list + "}]";
ggbApplet.evalCommand(comm1);
var comm2 = "SetValue[angle_{" + groups[i][0].value + "}+,0]";
ggbApplet.evalCommand(comm2);
}
function Angle(i, j) {
this.name = "angleA_" + i + "B_" + j;
var comm3 = "angleA_" + i + "B_" + j + " = Angle[" + lines[i] + "," + lines[j] + "]";
ggbApplet.evalCommand(comm3);
var val = ggbApplet.getValue(this.name);
if (val > 180) {
val -= 180;
}
this.value = val;
ggbApplet.setVisible(name, false);
}
Hopefully this helps!
Your function definition is missing the parameter list after the function name.
Also, you're initializing the elements property to an undefined value. You need to initialize it to an empty array, so that the add method can set elements of it.
function Set() {
this.elements=[];
this.size=0;
}
This does what I need it to, I am just tring to simplify it a little more. I designed this off off various things I found on the internet. Problem is if add more messages and do not adjust the number of messages in the loop it crashes at the end, I would like to get around that. any ideas?
var chatMessages = [chatMessage0 = "",
chatMessage1 = " this",
chatMessage2 = " is",
chatMessage3 = " almost",
chatMessage4 = " perfect",
chatMessage5 = " for what I need",
chatMessage999 = ""];
var chatMessageCount = 5;
var chatNow = [];
chat();
function chat() {
for (i = 0; i < chatMessageCount + 2; i++) {
chatNow = chatMessages[i];
if (chatNow.length > 0) {
alert(chatNow);
}
}
}
Demo
You don't need the chatMessageCount variable. Just use chatMessages.length.
var chatMessages = [
"",
" this",
" is",
" almost",
" perfect",
""];
function chat() {
for (var i = 0; i < chatMessages.length; i++) {
var chatNow = chatMessages[i];
if (chatNow != "") {
alert(chatNow);
}
}
}
DEMO
var select = [];
for (var i = 0; i < nameslots; i += 1) {
select[i] = this.value;
}
This is an extract of my code. I want to generate a list of variables (select1, select2, etc. depending on the length of nameslots in the for.
This doesn't seem to be working. How can I achieve this? If you require the full code I can post it.
EDIT: full code for this specific function.
//name and time slots
function gennametime() {
document.getElementById('slots').innerHTML = '';
var namelist = editnamebox.children, slotnameHtml = '', optionlist;
nameslots = document.getElementById('setpresentslots').value;
for (var f = 0; f < namelist.length; f += 1) {
slotnameHtml += '<option>'
+ namelist[f].children[0].value
+ '</option>';
};
var select = [];
for (var i = 0; i < nameslots; i += 1) {
var slotname = document.createElement('select'),
slottime = document.createElement('select'),
slotlist = document.createElement('li');
slotname.id = 'personname' + i;
slottime.id = 'persontime' + i;
slottime.className = 'persontime';
slotname.innerHTML = slotnameHtml;
slottime.innerHTML = '<optgroup><option value="1">00:01</option><option value="2">00:02</option><option value="3">00:03</option><option value="4">00:04</option><option value="5">00:05</option><option value="6">00:06</option><option value="7">00:07</option><option value="8">00:08</option><option value="9">00:09</option><option value="10">00:10</option><option value="15">00:15</option><option value="20">00:20</option><option value="25">00:25</option><option value="30">00:30</option><option value="35">00:35</option><option value="40">00:40</option><option value="45">00:45</option><option value="50">00:50</option><option value="55">00:55</option><option value="60">1:00</option><option value="75">1:15</option><option value="90">1:30</option><option value="105">1:45</option><option value="120">2:00</option></optgroup>';
slotlist.appendChild(slotname);
slotlist.appendChild(slottime);
document.getElementById('slots').appendChild(slotlist);
(function (slottime) {
slottime.addEventListener("change", function () {
select[i] = this.value;
});
})(slottime);
}
}
You'll have to close in the iterator as well in that IIFE
(function (slottime, j) {
slottime.addEventListener("change", function () {
select[j] = this.value;
});
})(slottime, i);
and it's only updated when the element actually change
The cool thing about JavaScript arrays is that you can add things to them after the fact.
var select = [];
for(var i = 0; i < nameSlots; i++) {
var newValue = this.value;
// Push appends the new value to the end of the array.
select.push(newValue);
}