function checkData() {
var temp = 0;
var totalMarks = countMark(temp);
if (totalMarks != 100)
window.alert("Marks must total 100");
}
function countMark(mark) {
var totalMark = 0;
totalMark += parseInt(mark)
return totalMark;
}
function doAdd() {
var taskid = document.getElementById("taskid").value;
var taskname = document.getElementById("taskname").value;
var taskmark = document.getElementById("taskmark").value;
if (taskid.length === 0)
window.alert("Task Id cannot be empty!");
if (taskname.length === 0)
window.alert("Task name cannot be empty!");
if (taskmark.length === 0)
window.alert("Task Mark cannot be empty!");
else if (!markpattern.test(taskmark))
window.alert("Invalid data in mark field");
var marks = parseInt(document.getElementById("taskmark"));
if (marks < 0 || marks > 100)
window.alert("Marks out of range. Please re-enter");
countMark(marks);
}
My question is when i keep call the doAdd() function. my marks will keep adding . want to do like passing reference like in C++ . my function countMark(...) will keep adding .
after that, when my form submitted, my form will call the function checkData()
If my totalmark is not 100 . will prompt out the alert and error.
but my code is not working . I guess that my countMark function wrong somewhere
If I understand you correctly, you're looking for the equivalent of a static variable - something that gets initialized the first time the function is called, and keeps it's value for subsequent calls.
Take a look at this related question: https://stackoverflow.com/a/1535650/2444111
The top answer (by CMS) is talking about class-based static variables, which are not quite the same thing.
The second answer (by Pascal MARTIN) is what you're looking for. It takes advantage of the fact that JS functions are also objects, and stores the variable as a property of the function object. This is a better solution than using a global variable (or a property of window, which is what a global actually is)
There are several issues in your code and it's really hard to say what your intention was. But I will address what I found.
In the following piece of code you are requesting a DOM Element and try to parse it as an Integer. The result of that type convertion is always NaN. Maybe wanted to get the value attribute of your element, like you did before. (Also, don't request the same element multiple times. Request it once, save the result in a variable and use that variable from that on).
var marks = parseInt(document.getElementById("taskmark"));
if (marks < 0 || marks > 100)
window.alert("Marks out of range. Please re-enter");
countMark(marks);
Your function countMark is pretty useless, because it will always return whatever Number you pass to it (see comments in your code).
function countMark(mark) {
var totalMark = 0; //create a new variable with value 0
totalMark += parseInt(mark) //add "mark" to that variable
return totalMark; //return that variable => 0 + mark = mark (and if mark = NaN => 0 + mark = NaN)
}
Maybe you wanted to make totalMark a global variable, than you would need to define it outside of your function:
var totalMark = 0;
function countMark(mark) {
totalMark += parseInt(mark);
return totalMark;
}
Last but not least, lets analyse your function checkData:
function checkData() {
var temp = 0; //create a local variable with value 0
var totalMarks = countMark(temp); //pass 0 to countMark => return 0 => totalMarks = 0
if (totalMarks != 100) //always true since totalMarks is always 0
window.alert("Marks must total 100"); //will always alert
}
Related
sorry this is a super basic question, but I'm not too familiar with google script yet so finding answers to these simple tasks is proving to be difficult. In this code, I'm trying to set a string of numbers to a variable based on another variable. AppNaming is the variable I'm trying to assign the numbers to. AppType is already defined earlier in the code, and depending on the type, I need it to take only part of the variable AppNumber. Depending on the AppType, the AppNumber is separated by commas or slashes, hence the indexOf parts. Are if statements not allowed with var functions? I need the var AppNaming to change based on the AppType in order to name a file later on in the code. Thanks for all the help and sorry again if these questions are annoying; I'm still learning.
function AutoFill(e) {
// variables all defined earlier
//Naming code
var AppNaming = if( AppType == '1' ){
AppNumber.substring( 0, AppNumber.indexOf(","))
}
else if ( AppType == '2'){
AppNumber.substring( 0, AppNumber.indexOf("/"))
}
else ( AppType == '3'){
AppNumber.substring( 0, AppNumber.indexOf(","))
}
You can only assign values to variables. Unfortunately, if statements are not values so you can't say var a = if (...) { } but you can say var a = 3
An if statement controls the flow of the application.
var something = 20;
var a;
if (something > 20) {
a = "this block runs if something is greater than 20";
} else if (something < 20) {
a = "this block runs if something is less than 20";
} else {
a = "this block runs otherwise";
}
// The value of 'a' is 'this block runs otherwise' at this point
So in your example, you can assign App.Number.substring(0, AppNumber.indexOf(",") to a variable because that expression will return a value.
I would recommend you to learn the basics of JavaScript.
I am having trouble returning a statement when my RegExp finds no matches :
function ai(message) {
if (username.length < 3) {
username = message;
send_message("Oh, well hello " + username + ", My name is Donald J Trump and i'm a big boy");
} else {
for (i = 0; i <= botChat.length; i++) {
var re = new RegExp(botChat[i][0], "i");
if (re.test(message)) {
var length = botChat[i].length - 1;
var index = Math.ceil(length * Math.random());
var reply = botChat[i][index];
send_message(reply);
}
}
}
}
When I enter a phrase it can correctly match the first line in an array as per the for loop. The issue I'm having is when I try to add an else statement it ceases to loop through my array properly.
I have tried :
else if (re.test(message) === false) {
send_message("i can't be expected to know everything");
}
But it doesn't work, it prevents the loop from looping past botChat[0][0].
I've also tried :
if (send_message().val() == "") {
// ...
}
But every time my code no longer works. Is there a method of adding something to my array that says 'if you don't find a match above, choose this'?
Or just a way of working my code so that the if/else works?
attached is the codepen.
I checked your codepen and the lines 190 and 194 console.log(send_message().val()); seems to be breaking the loop because those lines are throwing an exception since send_message() returns undefined and undefined does not have the .val() method.
Your regular expressions are working fine. I recommend not creating new RegExp objects every iteration, instead, use the one defined in the array if (botChat[i][0].test(message)), the overhead will be less.
I have a for loop that searches for a value in an array in my javascript code in couchDb. I want to make it into a function. This should be fairly simple but I am having trouble with it. This is the for loop(Which works perfectly fine):
if (newDoc.destination && newDoc.destination.length > 0) {
for (var i = 0; i < newDoc.destination.length; i++) {
if (newDoc.destination[i].address) return;
}
}
throw({forbidden: 'doc.address is required'});
And this is the way I wrapped it into a function:
function arrayReq(field, message) {
message = message || "Array must have a " + field;
if (newDoc.destination && newDoc.destination.length > 0) {
for (var i = 0; i < newDoc.destination.length; i++) {
if (newDoc.destination[i].field) return;
}
}
throw({forbidden: message});
}
I would think that the return in the function should stop the function from going any further but it still throws the error. Can someone tell me what I am doing wrong? Btw if i change field into address it works fine. Can I not make the address into a changeable variable?
I think the problem is that you are trying to use field as both a string variable, and a property of your object inside the destination[] array.
In your code, if the destination[i] object does not have a property called field (not the string value populated in the field parameter, but an actual property named "field") it will never evaluate to true and break out of the function.
To access a property of an object by using the string representation in javascript, you use the indexer syntax.
Try changing it from array.destination[i].field to array.destination[i][field]
EDIT I originally posted this with my version of the J.S but it's so far off no one can even help so i'm starting over. Here is the pseudocode i have done that needs to be translated into a Javascript program. Any help is appreciated!
I am a beginning programmer i understand this code will have multiple errors, that's why i am here. Array's and loops have given me much trouble while trying to learn them and especially with formatting them in JavaScript. The things i know are incorrect or still need i commented out i still need them, i also know i'm not passing anything i just can't seem to wrap my head around how to get them there. I'm also not sure if while gather input i'm using alter and prompt correctly. In the display function the spacing is necessary for when it will be displayed. Corrections and explanations are greatly appreciated.
Module main()
//Declare local variables
Declare endProgram = “no”
While endProgram == “no”
Declare Real notGreenCost[12]
Declare Real goneGreenCost[12]
Declare Real savings[12]
Declare String months[12] = “January”, “February”, “March”, “April”, “May”, “June”, “July”, “August”, “September”, “October”, “November”, “December”
//function calls
getNotGreen(notGreenCost, months)
getGoneGreen(goneGreenCost, months)
energySaved(notGreenCost, goneGreenCosts, savings)
displayInfo(notGreenCost, goneGreenCosts, savings, months)
Display “Do you want to end the program? Yes or no”
Input endProgram
End While
End Module
Module getNotGreen(Real notGreenCost[], String months[])
Set counter = 0
While counter < 12
Display “Enter NOT GREEN energy costs for”, months[counter]
Input notGreenCosts[counter]
Set counter = counter + 1
End While
End Module
Module getGoneGreen(Real goneGreenCost[], String months[])
Set counter = 0
While counter < 12
Display “Enter GONE GREEN energy costs for”, months[counter]
Input goneGreenCosts[counter]
Set counter = counter + 1
End While
End Module
Module energySaved(Real notGreenCost[], Real goneGreenCost[], Real savings[])
Set counter = 0
While counter < 12
Set savings[counter] = notGreenCost[counter] – goneGreenCost[counter]
Set counter = counter + 1
End While
End Module
Module displayInfo(Real notGreenCost[], Real goneGreenCost[], Real savings[], String months[])
Set counter = 0
While counter < 12
Display “Information for”, months[counter]
Display “Savings $”, savings[counter]
Display “Not Green Costs $”, notGreenCost[counter]
Display “Gone Green Costs $”, goneGreenCost[counter]
End While
End Module
A few notes:
Currently the program creates a few variables and functions that
don't seem to interact
Most of the edits below are not optimal - there are parts that
could be done by much simpler means (i.e. counter++) - But thats
for you to learn =P
I made quite a few assumptions of what you wanted the program to
do, they might be wrong, they might be right
var notGreenCost = []; //Array lengths don't need to be specified
var goneGreenCost = [];
var savings = [];
var months = ["January", "Feburary", "March", "April", "May", "June"];
//A boolean value (true | false) would suit this better as opposed to "yes"/ "no"
var endProgram = false;
var option = 0;
/* You dont need main functions in javascript
* migrated everything to be global :/
* Delete:
function main(){
// Move this (made it global): var endProgram = "no";
}
*/
// I don't think this is meant to be initMonths..
// Maybe something like getOptions?
function /*initMonths*/getOptions(){
while (endProgram == false){ //lowercase while
//Because prompt would block everything else until it gets input
//we probably want to move the prompt to be after the alerts
alert("options:"); //Clarity
alert("1 to enter data");
alert("2 to display data");
alert("3 to write data to a file");
alert("4 to read data from a file");
//Alter global "option" to take the value of the prompt
option = prompt("What would you like to do? Type:");
//} //I assume you want the rest of the code in this while loop - otherwise it will loop forever
// Delete this bracket (its unmatched): {
// Delete return statement as it will stop the function return option;
// Delete this bracket (its unmatched): }
//Create a variable to take the value of prompt (this should be outside the while loop) but it seem clearer for explanation purposes to be here
var toEnd;
toEnd = prompt("Do you want to end the program (enter yes or no)");
// Javascript uses != for "not equal to" and && for "AND"
while (toEnd != "no" && toEnd != "yes") {
toEnd = prompt("Please enter a value of yes or no");
}
//I think you want to assign the value of toEnd to endProgram
// Note the the below is not the only/best way to do it
if(toEnd == "no") {
endProgram = false;
} else if(toEnd == "yes") {
endProgram = true;
}
// While use brackets not End s
// End While
// End While
}//End while loop here
}
Javascript in a browser cannot alter files - writeToFile, readFromFile have all been removed
I believe you want months to be global, if it is then initMonths is unnecessary
getNotGreen:
function getNotGreen(){
//You don't need to specify types in Javascript
/*Integer*/ var counter = 0
while (counter < 6){ //lowercase while
//I'm assuming you want to combine the values of "Enter NOT GREEN energy costs for" and months[counter] - This is done by using the + sign
//Im also assuming you want to read the value into notGreenCost
//.push adds a value to a array
notGreenCost.push(prompt("Enter NOT GREEN energy costs for" + months[counter]))
//Returning here makes the rest of the function redundant
//}
//return notGreenCost[counter];
//}
//Javascript does not use Set
// Note that below is not the only/best way to do it
/*Set*/ counter = counter + 1
} //End the while loop here
}
getGoneGreen:
function getGoneGreen(){
//Counter should probably be local (not global) - use var
var counter = 0;
while (counter < 6){//lowercase while
//I'm assuming you want to combine the values of "Enter NOT GREEN energy costs for" and months[counter] - This is done by using the + sign
//Im also assuming you want to read the value into notGreenCost
//.push adds a value to a array
goneGreenCost.push(prompt("Enter GONE GREEN energy costs for" + months[counter]));
//See above (getNotGreen)
//}
//return goneGreenCost[counter];
/*Set*/ counter = counter + 1;
}//End while loop here
}
energySaved:
function energySaved(){
//Counter should probably be local (not global) - use var
var counter = 0;
while (counter < 6){//lowercase while
savings[counter] = notGreenCost[counter] - goneGreenCost[counter]
counter = counter + 1;
}
} //I assume you want to end energySaved here?
displayInfo:
function displayInfo(){
//Alert produced individual boxes, i assume you want the following in a single window?
// "\n" is a line break
alert("SAVINGS NOT GREEN GONE GREEN MONTH\n"+
"_________________________________________________\n");
//Counter should probably be local (not global) - use var
var counter = 0;
while (counter < 6){//lowercase while
alert( "$" + savings[counter] + "$" + notGreenCost[counter] + "$" + goneGreenCost[counter] + "" + months[counter]);
counter = counter + 1;
}
} //I assume you want to end displayInfo here?
I have some code here that will make validations of whether or not the input from a text box is NOT an empty string and isNaN. When i do these validations on amounts entered, i would like it to add them up.. however when a user does not enter anything in one or more amount fields the program should just add entered fields. But instead i get NaN showing in the total field.
link to full code: http://jsfiddle.net/KxNqQ/
var $ = function (id) {
return document.getElementById(id);
}
var calculateBills = function () {
var myErrorFlag = "N";
for (i = 1; i <= 4; i++) {
AmountNumber = 'amount' + i;
AmountValue = $(AmountNumber).value;
if (AmountValue != "" && isNaN(AmountValue)) {
$(AmountNumber).style.color = "red";
myErrorFlag = "Y";
} else {
$(AmountNumber).style.color = "black";
myErrorFlag = "N";
}
}
if (myErrorFlag != "Y") {
var Amount = 0;
for (i = 1; i <= 4; i++) {
Amount += parseInt($('amount' + i).value,10);
}
$('total').value = Amount;
}
}
var clearFields = function () {
for (i = 1; i <= 4; i++) {
itemName = 'item' + i;
$(itemName).value = "";
}
for (i = 1; i <= 4; i++) {
amountName = 'amount' + i;
$(amountName).value = "";
}
$('total').value = "";
}
window.onload = function () {
$("clearfields").onclick = clearFields;
$("addbills").onclick = calculateBills;
}
I think you've got your requirements a little bit confused, or at the very least I was confused by them. So in order to answer your question, I'm going to rephrase the requirements so I understand them better. This is a useful exercise that I try to do when I'm not 100% sure of the requirements; if I can't get the requirements right, what's to say I'll get the code right?
So the requirements – as I understand them – are:
Given each amount input
When the input has a value
And that value is a number
Then add the value to the total
And make the input color black
But if the input does not have a value
Or that value is not a number
Then make the input color red
Going through your code, I can see a number of problems with it. First, I noticed that both AmountNumber and AmountValue are global variables, because they were not declared local with the var keyword. So before fixing our code, let's change that. Let's also change the variable names to something that more accurately describe what they are, hopefully making the code easier to understand:
var input = $('amount' + i);
var value = input.value;
Now, note that I chose to store the element in the input variable. This is so we don't have to look it up multiple times within the loop. Looking things up in the DOM can be expensive so we'll want to keep it to a minimum. There are other was to look up elements as well, such as getElementsByClassName, querySelector and querySelectorAll; those are left as an exercise for the reader to research and evaluate.
Next, in each iteration of the loop, you check that AmountValue is not a string and simultaneously is not a number:
if (AmountValue != "" && isNaN(AmountValue)) {
This will be true so long as AmountValue is truthy (which is the case for non-empty strings) and so long as isNaN thinks it's a number (which is the case for strings that contain numbers.) It really is rather confusing; if I understand your code correctly this clause is there to check for invalid input and if it is true should mark the input field red and set a flag. I.e. this is the but clause in the aforementioned requirements.
Let's rewrite this to be the when clause instead, we'll take care of the but later. Before we do that, let's look at the myErrorFlag. It's used – I think – to see whether all input is well formed and in that case, add it all up. Well, validation and summation can be done in one fell swoop, so let's get rid of the flag and sum the values while validating them. So we replace myErrorFlag with a total variable:
var total = 0;
Now, let's get back to our clause. The requirements say:
When the input has a value
And that value is a number
Then add the value to the total
In code, that should look something like this:
if (value && !isNaN(value)) {
total += parseInt(value, 10);
input.style.color = 'black';
}
There are a couple of things going on here. For one, the if statement has been turned on its head a bit from what it was. It first checks to see that value is truthy, then that it is a number. The second check can be a bit tricky to read, because it is essentially a double negation; in english it reads "is not not a number", i.e. "is a number". I'll leave it as an exercise for the reader to figure out whether there's a more easily understood way of writing this check.
Now what about the but clause in our requirements?
But if the input does not have a value
Or that value is not a number
Then make the input color red
Well, it's essentially the inverse of our previous statement, so let's simply add an else clause:
else {
input.style.color = 'red';
}
Because the requirements doesn't mention the total variable in this clause, it is simply ignored and doesn't show up in the end result.
Adding it all up (no pun intended) the code – with comments – looks like this:
var calculateBills = function () {
var total = 0;
for (i = 1; i <= 4; i++) {
// Given each amount input
var input = $('amount' + i);
var value = input.value;
if (value && !isNaN(value)) {
// When the input has a value
// And that value is a number
// Then add the value to the total
total += parseInt(value, 10);
// And make the input color black
input.style.color = 'black';
} else {
// But if the input does not have a value
// Or that value is not a number
// Then make the input color red
input.style.color = 'red';
}
}
$('total').value = total;
};
There are more things that could be learned from this to make for better code. For instance, this code will break if the number of inputs change, or if their id names change. This is because they are selected specifically by their IDs and as such, if those change then this code will no longer function.
Another potential issue is that we're setting inline styles on the inputs as we loop over them. This means that in order to keep this code up to date with the styling of the site, it'll have to change. Generally, mixing styling and functionality like this is not a good idea and should be avoided. One way of doing so is to use class names instead, and toggle these on and off. Incidentally, this could also help the previous problem I mentioned.
There are other problems as well, but we'll leave those for another day. Hope this helps!
Try this
var calculateBills = function () {
var Amount = 0;
for (i = 1; i <= 4; i++) {
var AmountElement = $('amount' + i),
AmountValue = AmountElement.value;
if (AmountValue != "" && !isNaN(AmountValue)) {
AmountElement.style.color = "red";
Amount += parseInt(AmountValue,10);
} else {
AmountElement.style.color = "";
}
}
$('total').value = Amount;
};
Demo
Anyway, instead of using elements with id like id="amount1", id="amount2", id="amount3", etc., you could use classes (e.g class="amount") and get them with .getElementsByClassName