why my last if condition is not working to show validity error, if user input no value. Actually i am beginner in js making calculator as practice. I shall be very thankful if anyone could resolve it.
function calc()
{
let n1 = parseFloat(document.getElementById('n1').value);
let n2 = parseFloat(document.getElementById('n2').value);
let oper = document.getElementById('operators').value;
if(oper === '+')
{
document.getElementById('result').value = n1+n2;
}
if(oper === '-')
{
document.getElementById('result').value = n1-n2;
}
if(oper === '/')
{
document.getElementById('result').value = n1/n2;
}
if(oper === 'X')
{
document.getElementById('result').value = n1*n2;
}
if(n1=="" || n2==""){
document.getElementById("error").innerHTML="invalid input";
return true;
}
else{
return false;
}
Probably it happens because it reacts to the condition next to the last one where you have n1=="" || n2==""
Related
I have solved the problem Count the smiley faces:
Given an array (arr) as an argument complete the function countSmileys that should return the total number of smiling faces.
Rules for a smiling face:
Each smiley face must contain a valid pair of eyes. Eyes can be marked as : or ;
A smiley face can have a nose but it does not have to. Valid characters for a nose are - or ~
Every smiling face must have a smiling mouth that should be marked with either ) or D
No additional characters are allowed except for those mentioned.
Valid smiley face examples: :) :D ;-D :~)
Invalid smiley faces: ;( :> :} :]
Example
countSmileys([':)', ';(', ';}', ':-D']); // should return 2;
countSmileys([';D', ':-(', ':-)', ';~)']); // should return 3;
countSmileys([';]', ':[', ';*', ':$', ';-D']); // should return 1;
Note
In case of an empty array return 0. You will not be tested with invalid input (input will always be an array). Order of the face (eyes, nose, mouth) elements will always be the same.
Then when I look through the solutions I find that many people use regexp. Then I want write a state machine to implement regexp and solve this problem. But I failed. This is my code:
function countSmileys(smileys) {
let state = smileyHasValidEye;
return smileys.filter(smiley => {
for (let s of [...smiley]) {
state = state(s);
}
return state === true;
}).length;
}
function smileyHasValidEye(s) {
if (s === ':' || s === ';') {
return smileyHasValidNose;
}
return smileyHasValidEye;
}
function smileyHasValidNose(s) {
if (s === '-' || s === '~') {
return smileyHasValidMouth;
}
return smileyHasValidMouth(s);
}
function smileyHasValidMouth(s) {
if (s === ')' || s === 'D') {
return true;
}
return;
}
console.log(countSmileys([':)', ';(', ';}', ':-D']));
And the error I get is:
state = state(s);
^
TypeError: state is not a function
Then I debugged my code I found the procedure doesn't enter the smileyHasValidNose function. Then I don't know the reason.
The problem is you don't really reset state in between smileys. So the next smiley state will be true which you can't call (it's not a function).
You could use a local variable for state that resets it to the first function (the first step).
function countSmileys(smileys) {
let firstStep = smileyHasValidEye;
return smileys.filter(smiley => {
let state = firstStep;
for (let s of [...smiley]) {
state = state(s);
}
return state === true;
}).length;
}
function smileyHasValidEye(s) {
if (s === ':' || s === ';') {
return smileyHasValidNose;
}
return smileyHasValidEye;
}
function smileyHasValidNose(s) {
if (s === '-' || s === '~') {
return smileyHasValidMouth;
}
return smileyHasValidMouth(s);
}
function smileyHasValidMouth(s) {
if (s === ')' || s === 'D') {
return true;
}
return;
}
console.log(countSmileys([':)', ';(', ';}', ':-D']));
This code however, will error if there's more on the string besides the smiley (or a partial of the smiley).
I would change smileyHasValidMouth to return false if it doesn't detect a smiley. Just to be more consistent here...
function smileyHasValidMouth(s) {
if (s === ')' || s === 'D') {
return true;
}
return false;
}
And adjust your loop to exit early if it finds a value that is not a function.
for (let s of [...smiley]) {
state = state(s);
if(typeof state !== 'function') return state;
}
function countSmileys(smileys) {
let firstStep = smileyHasValidEye;
return smileys.filter(smiley => {
let state = firstStep;
for (let s of [...smiley]) {
state = state(s);
if (typeof state !== 'function') return state;
}
}).length;
}
function smileyHasValidEye(s) {
if (s === ':' || s === ';') {
return smileyHasValidNose;
}
return smileyHasValidEye;
}
function smileyHasValidNose(s) {
if (s === '-' || s === '~') {
return smileyHasValidMouth;
}
return smileyHasValidMouth(s);
}
function smileyHasValidMouth(s) {
if (s === ')' || s === 'D') {
return true;
}
return false;
}
console.log(countSmileys([':~(', ':>', ':D', ':(', ':o>', ';)', ':)']));
Intro
So I have stumbled across this problem yesterday, and I've been stumped trying to figure this out myself. I only have this problem with JavaScript.
Problem
I've been creating a programming language with JS since the start of this week, and I was enjoying myself the entire week making it. The problem here is that when I carry dictionaries across functions, it has some problems reading and writing into those dictionaries. When I check the console logs, I see that not just the dictionary in the function was written, but all of the instances of that dictionary were written.
Code
Here is the code to graph.js:
function codeToArray(code) {
let codeArray = {commands:[], vars:{x:{value:0, read_only:true},y:{value:0, read_only:false}}};
let commands = code.split("\n");
for (i = 0; i < commands.length; i++) {
let command = commands[i];
let inputs = command.split(" ");
if (inputs[0].toLowerCase() !== ";") {
// Arithmetics
if (inputs[0].toLowerCase() === "+") { // Addition
codeArray.commands.push({name:"add", variable:inputs[1], value:inputs[2], syntax_id:1});
} else if (inputs[0].toLowerCase() === "-") { // Subtraction
codeArray.commands.push({name:"subtract", variable:inputs[1], value:inputs[2], syntax_id:1});
} else if (inputs[0].toLowerCase() === "*") { // Multiplication
codeArray.commands.push({name:"multiply", variable:inputs[1], value:inputs[2], syntax_id:1});
} else if (inputs[0].toLowerCase() === "/") { // Division
codeArray.commands.push({name:"divide", variable:inputs[1], value:inputs[2], syntax_id:1});
}
// I/O
else if (inputs[0].toLowerCase() === ":") { // Set
codeArray.commands.push({name:"set", variable:inputs[1], value:inputs[2], syntax_id:1});
}
// Conditional Statements
else if (inputs[0].toLowerCase() === "if") { // If Statement
let ifCommand = "";
for (j = 4; j < inputs.length; j++) {
if (j > 4) {
ifCommand += " " + inputs[j];
} else {
ifCommand += inputs[j];
}
}
let ifCommandArray = codeToArray(ifCommand).commands[0];
codeArray.commands.push({name:"if", value1:inputs[1], condition:inputs[2], value2:inputs[3], command:ifCommandArray, syntax_id:2});
}
}
}
return codeArray
}
function parseValue(value, variables) {
let return_value = value;
console.log(value);
console.log(variables);
if (value.charAt(0) === "$") {
let variable_name = return_value.substring(1, value.length);
console.log(variable_name);
let variable = variables[variable_name];
console.log(variable);
if (variable === undefined) {
return_value = NaN;
} else {
return_value = variable.value;
}
} else {
return_value = parseFloat(value);
}
console.log(return_value);
return return_value
}
function runCodeArray(commands, variables) {
for (i = 0; i < commands.length; i++) {
let command = commands[i];
if (command.syntax_id === 1) { // Simple Syntax (Variable Value Syntax)
if (command.name === "add") { // Addition
let variable = variables[command.variable];
if (variable === undefined) {
let error_message = `Variable cannot be found (line ${i+1} ignoring comments)`;
return {commands:commands, variables:variables, return_message:error_message};
}
if (variable.read_only === true) {
let error_message = `A read-only variable was trying to be written (line ${i+1} ignoring comments)`;
return {commands:commands, variables:variables, return_message:error_message};
}
let value = parseValue(command.value, variables);
if (value === NaN) {
let error_message = `The value parameter is invalid (line ${i+1} ignoring comments)`;
return {commands:commands, variables:variables, return_message:error_message};
}
variable.value += value;
} else if (command.name === "set") { // Set
let variable = variables[command.variable];
if (variable === undefined) {
variables[command.variable] = {value:0, read_only:false};
variable = variables[command.variable];
}
if (variable.read_only === true) {
let error_message = `A read-only variable was trying to be written (line ${i+1} ignoring comments)`;
return {commands:commands, variables:variables, return_message:error_message};
}
let value = parseValue(command.value, variables);
if (value === NaN) {
let error_message = `The value parameter is invalid (line ${i+1} ignoring comments)`;
return {commands:commands, variables:variables, return_message:error_message};
}
variable.value = value;
}
}
}
return {commands:commands, variables:variables, return_message:true};
}
var url_string = ...graph.html?pattern=%3A+a+42%0D%0A%3A+b+%24a%0D%0A%3A+c+%24b%0D%0A // window.location.href;
var url = new URL(url_string);
var pattern = url.searchParams.get("pattern");
let codeArray = codeToArray(pattern);
// console.log(codeArray);
let codeArrayOut = runCodeArray(codeArray.commands, codeArray.vars); // Will return true in return_message if everything is good, and will return a string in return_message if an error occurs.
// console.log(codeArrayOut);
if (codeArrayOut.return_message !== true) {
alert("Error: " + codeArrayOut.return_message);
}
Sorry if the code is too long, boring or messy for you to read. Here is the function that's causing the most problems:
function parseValue(value, variables) {
let return_value = value;
console.log(value);
console.log(variables);
if (value.charAt(0) === "$") {
let variable_name = return_value.substring(1, value.length);
console.log(variable_name);
let variable = variables[variable_name];
console.log(variable);
if (variable === undefined) {
return_value = NaN;
} else {
return_value = variable.value;
}
} else {
return_value = parseFloat(value);
}
console.log(return_value);
return return_value
}
Outro
I'm still learning in JavaScript, so I hope that you can solve this problem (because I can't).
everything is working properly only the control is not moving to the if statement
let fnum, snum, operator;
const op = ["+", "-", "*", "/", "%"];
let fnumUi = document.getElementById("fnumUI");
let snumUi = document.getElementById("snumUI");
let opUi = document.getElementById("opUI");
var input = document.getElementById("user_input");
let scoreUi = document.getElementById("score");
input.addEventListener("keypress", myFunction(event));
function myFunction(event) {
let answer = 8;
if (event.keyCode === 13) {
let user_ans = Number(input.value);
input.value = '';
fnum = Number(Math.floor(Math.random() * 20));
snum = Number(Math.floor(Math.random() * 20));
operator = op[Math.floor(Math.random() * op.length)];
fnumUi.innerHTML = fnum;
snumUi.innerHTML = snum;
opUi.innerHTML = operator;
if (operator === "+") {
answer = fnum + snum;
} else if (operator === "-") {
answer = fnum - snum;
} else if (operator === "*") {
answer = fnum * snum;
} else if (operator === "/") {
answer = fnum / snum;
} else {
answer = fnum % snum;
}
if (answer === user_ans) {
scoreUi.innerHTML = Number(scoreUi.innerHTML) + 3;
} else {
scoreUi.innerHTML = scoreUi.innerHTML - 1;
}
}
}
answer is updating but for this part of code
if (answer === user_ans) {
scoreUi.innerHTML = Number(scoreUi.innerHTML) + 3;
} else {
scoreUi.innerHTML = scoreUi.innerHTML - 1;
}
even when i write the correct answer it moves to else statement. not getting into if statement
so instead of adding 3 in score it is deducting 1 from the score.
You need to pass the function itself rather than the results of its call.
input.addEventListener("keypress",myFunction);
I'm trying to have someone guess a number from 1 to 6. I give them two tries if, by the end of the second try, they don't get it, then else will tell them what the number is but it just won't run. what am I doing wrong?
var number = Math.floor(Math.random() *6) +1;
var answer = false;
var guess = prompt('Take a guess, pick a number from 1 to 6');
if(parseInt(guess) === number) {
answer === true;
} else if (parseInt(guess) > number) {
var guessLess = prompt('To high! Guess less');
if (parseInt(guessLess) === number) {
answer === true;
} else if (parseInt(guess) < number) {
var guessMore = prompt('Guess more');
if(parseInt(guessMore) === number) {
answer = true;
}
}
}
if (answer) {
alert('You got it')
} else {
alert('No. The number was ' + number);
}
}
You are using comparison instead of assignment in the below segment
if (parseInt(guessLess) === number) {
answer === true;
Change it to
if (parseInt(guessLess) === number) {
answer = true;
Idealy, I would like my little project to have the memory functions M-, M+, MR and MC.
I was thinking of separate functions and variables to hold the M- and M+.
Is this a normal approach or there is a better one ?
Any idea what might be wrong with my script ? if there is something wrong ?
the number-display ID is the actual calculator screen
the code is :
$(document).ready(function(){
var display = "";
var operators = ["/", "*", "-", "+"];
var decimalAdded = false;
$("button").click(function() {
var key = $(this).text();
//update screen by adding display string to screen with maximum 19 numbers viewable
function updateDisplay() {
if (display.length > 19) {
$("#number-display").html(display.substr(display.length - 19, display.length));
} else {
$("#number-display").html(display.substr(0, 19));
}
}
//clear all entries by resetting display and variables
if (key === "AC" || key === "ON" || key === "MC") {
decimalAdded = false;
display = "";
$("#number-display").html("0");
}
else if (key === "OFF") {
decimalAdded = false;
display = "";
$("#number-display").html("");
}
//clear previous character and reset decimal bool if last character is decimal
else if (key === "CE") {
if (display.substr(display.length - 1, display.length) === ".") {
decimalAdded = false;
}
display = display.substr(0, display.length - 1);
updateDisplay();
}
//add key to display if key is a number
else if (!isNaN(key)) {
display += key;
updateDisplay();
}
//check that . is the first in the number before adding and add 0. or just .
else if (key === ".") {
if (!decimalAdded) {
if(display > 0){
display += key;
}
else {
display += "0" + key;
}
decimalAdded = true;
updateDisplay();
}
}
//if key is basic operator, check that the last input was a number before inputting
else if (operators.indexOf(key) > -1) {
decimalAdded = false;
//first input is a number
if (display.length > 0 && !isNaN(display.substr(display.length - 1, display.length))) {
display += key;
updateDisplay();
}
// allow minus sign as first input
else if (display.length === 0 && key === "-") {
display += key;
updateDisplay();
}
}
// calculate square root of number
else if ( $(this).id === "sqrt") {
var tempStore = display.html();
$("#number-display").html(eval(Math.sqrt(tempStore)));
decimalAdded = false;
}
// change sign of number
else if ($(this).id === "plusmn") {
var newNum = display * -1;
$("#number-display").html(newNum);
}
// create memory plus and minus and calculate MR
else if (key === "M-") {
}
else if (key === "M+") {
}
// percentage function
else if (key === "%"){
}
else if (key == "=") {
//if last input is a decimal or operator, remove from display
if (isNaN(display.substr(display.length - 1, display.length))) {
display = display.substr(0, display.length - 1);
}
var calc = display;
calc = eval(calc);
display = String(calc);
if (display.indexOf('.')) {
decimalAdded = true;
} else {
decimalAdded = false;
}
$("#number-display").html(display);
}
});});
One alternative is a switch statement, which would look something like:
switch (key) {
case "M-":
// do stuff
break;
case "M+":
// do stuff
break;
case "%":
// do stuff
break;
case "=":
// do stuff
break;
}
More documentation on MDN: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/switch