Can't understand how I possibly can check value given in function. All my known methods fails. Sorry for lame question!:)
# doesn't work, but should to
window.mobilecheck = function() {
return true;
}
if (window.mobilecheck==true) {
alert('true');
}
# works, but shouldn't
window.mobilecheck = function() {
return false;
}
if (window.mobilecheck) {
alert('true');
}
# doesn't work, but should
window.mobilecheck = function() {
return 1;
}
if (window.mobilecheck==1) {
alert('true');
}
So how to check if function returns true or false if this doesn't work?
When you use window.mobilecheck you get the function, not the evaluation/return value of the function. Use to window.mobilecheck() ==1 to evaluate your function.
Related
Problem
I've tried multiple avenues and watched videos. I'm stuck...
function exerciseThree(typeOfPizza){
let lovesPizza;
// In this exercise, you will be given a variable, it will be called: typeOfPizza
// You are also given another variable called: lovesPizza;
// Using an if/else statement assign lovesPizza to true if typeOfPizza is 'pepperoni', assign it to false if it is 'olives'
What I've tried:
if (lovesPizza==='pepperoni') {
// The value is empty.
return true;
}
else {
(lovesPizza==='olives')
return false;
}
Another attempt
// if(lovesPizza===pepperoni){
// return true
//}
//else (lovesPizza===olives){
// return false
// }
Another one
//if (lovesPizza.equals(pepperoni))
// return "true";
//else (lovesPizza.equals(olives))
// return "false"
As the comments say, you're looking for if / else. You should also double check your reading of the question, you had your checking / assigning variables the wrong way around
function exerciseThree(typeOfPizza){
let lovesPizza;
if (typeOfPizza === 'pepperoni') {
lovesPizza = true;
} else if (typeOfPizza === 'olives') {
lovesPizza = false;
}
console.log('lovesPizza:', lovesPizza);
};
exerciseThree('pepperoni');
exerciseThree('olives');
I would highly recommend using a switch statement in this case here. Switch statements run faster and are easier to work with in my opinion.
But to point out what you're doing wrong:
Here you are checking if lovesPizza has the value of pepperoni. But you should be checking typeOfPizza. This is why you're most likely getting undefined:
if (lovesPizza==='pepperoni') {
// The value is empty.
return true;
}
else {
(lovesPizza==='olives')
return false;
}
Check out how this looks with a switch statement.
function exerciseThree(typeOfPizza) {
switch (typeOfPizza) {
case 'pepperoni':
return true;
case 'olives':
return false;
default:
return false;
}
}
exerciseThree('pepperoni');
exerciseThree('olives');
Your else statement needs an if
if(somethingisTrue)
{
return "it is true";
}
else if(somethingelseistrue)
{
return "no the other thing was true";
}
else
{
return "nothing is true"
}
Also === checks the strings equal and are both strings. It is often better to make sure the if is case insensative
if(!typeOfPizza)
{
//raise an error as null was passed in
return "false"
}
else if(typeOfPizza.toLowerCase().trim()==="pepperoni"){
{
return true..... you can build the rest
I often write a function (prototype) called cleanString or compareString to perform all the normal cleaning up of strings.
A simple solution is but doesn't use ifs as asked.
function exerciseThree(typeOfPizza){
let lovesPizza= typeOfPizza==="pepperoni";
return lovesPizza;
}
I certainly hope you teacher is playing a trick on you.
There is no sane suggestions what to do if you send for instance 'ham' into it, and not handle all possibilities are just sloppy.
let lovesPizza;
function exerciseThree(typeOfPizza){
if(typeOfPizza === 'pepperoni') {
return true;
} else if (typeOfPizza === 'olives') {
return false;
} else {
return undefined;
}
}
lovesPizza = exerciseThree('pepperoni');
console.log(lovesPizza); // true
lovesPizza = exerciseThree('olives');
console.log(lovesPizza); // false
lovesPizza = exerciseThree('ham');
console.log(lovesPizza); // undefined
In the following code, how the statement works, as this statement is the part of an javascript file.
this.isSelected = function(checkTab)
{
return(this.tab===checkTab);
}
this.isSelected is a function, taking checkTab as a parameter. It compares it to this.tab and returns true if they are equal, otherwise false.
this.isSelected = function(checkTab)
{
return (this.tab === checkTab);
}
// equivalent to
function isSelected(checkTab) {
if(this.tab === checkTab) return true;
return false;
}
I cant seem to get this function to return true even after ticking the two check boxes I have on the page. I've been working on this for hours now and running out of ideas. Any help would be much appreciated.
if(myfunction() == true){
alert('YAY!');
}
function myfunction(){
if($("input[type=checkbox]").length > 0){
$('.checkbox').each(function(){
if($(this).prop('checked')){
return true;
}
else{
$(this).find(".CheckboxCheck").show();
return false;
}
});
}
else{
return true;
}
}
You are returning true from within the function that you passed to each, not from myfunction. Except in the case that there are no check boxes on your page, and thus the else block executes in myfunction, myfunction is returning undefined.
You can do something like this however:
if(myfunction() == true){
alert('YAY!');
}
function myfunction(){
var returnValue = true;
if($("input[type=checkbox]").length > 0) {
$('.checkbox').each(function(){
if($(this).prop('checked')){
returnValue = true;
return false; // Stops the each loop.
}
else {
$(this).find(".CheckboxCheck").show();
returnValue = false;
return false; // Stops the each loop.
}
});
}
return returnValue;
}
Now, I'm not exactly sure of what you're trying to do, and you will almost certainly need to tweak the code above. I'm just providing it as a way to illustrate how to get a value out of the function passed to each. If you're trying to determine if all of the checkboxes are checked, for example, then you'll want your each function to look something like this:
var returnValue = true;
...
$('.checkbox').each(function() {
if (!$(this).prop('checked')) {
returnValue = false;
return false;
}
});
EDIT: After looking at the second code snippet again, I realized that the each loop is unnecessary. If you want to determine if all check boxes are checked, all you need is this:
if ($('.checkbox:not(:checked)').length == 0) {
// All .checkbox elements are checked.
}
Now, keep in mind that the :not() and :checked selectors can't utilize the native JS functions, so they are slower, but probably not enough to matter. I prefer the conciseness.
Returning from inside the each callback function will not return from the outer function. The function will return undefined as you haven't specified any return value for it, and that is not equal to true.
You can use a variable for the result, that you set from within the loop:
function myfunction(){
var result = true;
$('.checkbox').each(function(){
if(!$(this).prop('checked')){
result = false;
$(this).find(".CheckboxCheck").show();
return false; // exit the loop
}
});
return result;
}
I have javascript with global variable declared:
var IsUserAllowed = false;
And I have a function:
function setSelectedIdsInput(inputLogicalId) {
if (IsUserAllowed) {
This does not work, I assume the value of IsUserAllowed is in string.
So i did:
var isUserAllowedStr = IsUserAllowed.toString().toLowerCase();
if (isUserAllowedStr == "true") {
This works, Since im new to java script i wanted to know if its ok to compare strings like this.
This due to fact that doing:
if (isUserAllowedStr.localeCompare("true")) {
Did not work either !
Thanks!
Update - i suspect the global var was string and not Boolean. this why the if failed. when i did alert(IsUserAllowed) the output was "False"
var IsUserAllowed = false;
then
function setSelectedIdsInput(inputLogicalId) {
if (IsUserAllowed) {
// something true
} else {
// something false
}
or
if(IsUserAllowed === true)
but it is useless.
Try:
if (isUserAllowed === true) {
}
isUserAllowed is a boolean (true / false):
You can check it by simply doing
if (isUserAllowed) { }
Or
if (isUserAllowed === true) { }
Your example should work as expected.
You can play around in this JSFiddle to test for yourself: http://jsfiddle.net/bT8hV/
var IsUserAllowed = false;
function setSelectedIdsInput() {
if (IsUserAllowed) {
alert('TRUE');
}
else {
alert('FALSE');
}
};
setSelectedIdsInput();
Is it possible to avoid declaring global variable and instead assign it the result of the anonymous function?
var logged = false;
Ext.each(userRecords, function (userRecord) {
if (userRecord.get('id') == currentuser) {
if (userRecord.get('password') == currentuserpassword) {
logged = true;
}
}
});
Example:
var logged = Ext.each(userRecords, function (userRecord) {
if (userRecord.get('id') == currentuser) {
if (userRecord.get('password') == currentuserpassword) {
return true;
}
}
});
If you're using Ext JS 4.0 or later, just replace your Ext.each in the second code block with Ext.Array.some and your code will work as is.
Executes the specified function for each array element until the function returns a truthy value. If such an item is found, the function will return true immediately. Otherwise, it will return false.
Using ECMAScript 5 some array method:
var logged = userRecords.some(function (userRecord) {
if (userRecord.get('id') == currentuser) {
if (userRecord.get('password') == currentuserpassword) {
return true;
}
}
return false;
});