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Bad Assignment, Logical Operators [closed]
Am learning Javascript in code academy. This is the test I have been given,
"Inside the eat function, create an if statement that returns true only if both hungry and foodHere are true, and false otherwise."
My code below is executing but it has a warning. What could be the problem?
- 1 = is an assignment operator. == is a comparison operator. Even better, use !foodHere instead of foodHere == false . Up to you to figure out what ! means. – Evan Trimboli Commented Feb 12, 2014 at 10:08
- they say nothing about a console.log ;-) – Philipp Sander Commented Feb 12, 2014 at 10:20
4 Answers 4
the problem was, that you tried to assign a value in the condition foodHere = false . If you want to compare things you need == and if you want to be sure that the types are the same use === . But you don't need that condition at all!
The assignment want you to return a boolean value ( true or false ) and not to print something, so i guess your code should look like this:
Single = is for assignment, == is for comparison
Anyways, you don't need the second comparison since if the first one is false it will always go through the else
I just want to give additional information for emilioicai's answer, there are two kind of "equal comparison" in JavaScript
- equal to ( == )
- exactly equal to ( === )
Reference: http://www.w3schools.com/js/js_comparisons.asp
= is for assignment, == is for value comparison and === is for value and datatype comparison. So you can use == while comparing with the false. But this is not the best practice. We always uses '!' negation operator while converting true to false
I am using || operator assuming that any one needs to be false.You can go for && if both false are required
Not the answer you're looking for? Browse other questions tagged javascript or ask your own question .
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Code.org, Boolean expression problem
I’m on code.org & I’m having a hard time with Boolean expressions, I know my codes messed up but I don’t know why.; my assignment is making two drop downs that work. Once a submit button is pressed the text area will tell you what exotic animal you are based on if you're an extrovert or introvert & your gender. I’m obviously doing something wrong because once I pick any of the options it immediately goes to else & says “You should get a Coati” please help me, thank you in advance. My code :
onEvent("submit", "click", function( ) { vert = getText("vertDropDown"); if ((vert=="Introvert" && gender=="Male")) { exoticAnimal= "hegehog"; } else if (vert&& ("genderDropDown"=="Female")) { exoticAnimal= "axolotl"; } else if (vert&& ("genderDropDown"=="Male")) { exoticAnimal= "fennec fox"; } else if ((vert&&("genderDropDown"=="Female") )) { exoticAnimal= "hyacinth macaw"; } else { exoticAnimal= "coati"; } setText("output","You should get a "+ exoticAnimal); });
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: bad expression: Invalid left-hand side in assignment
[[Open door|Sorter1][$CurrentPos.LocEntry[3] = 5; $CurrentPos.LocWall[3] = 5; $Reset = true; $DoorOpened = true]]
Originally I did try that normal link code method and what i was trying to achieve wasn't working so i wrongly assumed that you couldn't have [] within the link|passage code because it uses them, i was assuming it wasn't passing the values.
// WRONG: The closing square bracket of the array touches the closing pair of the markup, making them ambiguous. [[Go where?|There][$list to ["A", "B"]]] // CORRECT: The closing square bracket of the array is separated from the closing pair of the markup by a space. [[Go where?|There][$list to ["A", "B"] ]]
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What does "bad invocation" typically mean in JS?
I got this notice when I was trying to print out the substring “Melbourne is” from “Melbourne is great”.
console.log("Melbourne is great"(0, 12));
Answer 5382d491631fe9ed34006a4a
When JS sees "Melbourne is great"(0, 12) , it tries to “invoke” (call) "Melbourne is great" assuming it to be a function, and then when it sees that it is not a function, it complains of “bad invocation”.
Good spotting!
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What does "read only" mean as an error message?
we are getting a read only error message for variables. please help me. what does this mean? and how do we debug it? thanks!
It means you are using a variable name that code.org is also using for their stuff too. I think this is a mistake made by a developer and have already opened a bug months ago.
There is nothing to debug you just change the variable name you are using. For example name and location cannot be used by students. Speed is a function used by the turtle graphics package, so that can’t be used by students.
@sandiferc What variable names are you getting the read-only error for? Please share a link with the code. Also, take look at the App Lab documentation . It has detailed instructions on how to use the interface. Please let us know if you have more questions.
thank you!! very helpful
thank you!! i took a javascript course this summer and am understanding things more deeply now.
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COMMENTS
You can view student progress for entire lessons: Or zoom in to look at student progress on individual levels: To change the granularity of the view between lessons and levels, use the "View By" toggle button next to the " Select a course or unit " dropdown menu. The type of each level is denoted in the bar at the top of the progress table:
How to automatically play "Read-Aloud" instructions for students. My students are receiving a message regarding age restrictions. How do I turn this off? My students are receiving a message stating, "Your teacher didn't expect you to be here..." NEW: "End-of-lesson" boundaries to better control student pacing.
To see the last time a student in one of your sections worked on an assigned course, go to the individual level you want to check first. Then do the following: Open the blue Teacher Panel on the right-hand side of the page by clicking on the white arrow. Select the student you want to view progress for in the blue panel that appears.
I came here looking for that answer too. There does not seem to be a way to assign a project to students (not a course, as the previous reply answered). My students are using the Pre-Reader course, so none of the project areas are suitable for them except the Pre-Reader Playlab and the Pre-reader Artist.
I think that this is why its cool that students will see code in many different situations during the year in CSD. The code in unit 3 has to be syntactically correct and is procedural(for the most part runs from top to bottom) in nature. The code in unit 4 and 6 also has to be syntactically correct but is event driven. My two cents.
I would also make sure if they are in the same version of the curriculum (20-21). If those all seem to align, write to [email protected] with specific details like the student name, lesson and levels where you are having the issue. They can take a look at what is going on.
Equality operator. Category: Math. Your apps will sometimes need to check if the values in their code are equivalent or not, and then possibly perform some specific action using an if, if-else, or while block. == returns true if the value on the left-hand side of the operator is equal to the value on the right-hand side of the operator.
Step 3: [First-time only] Authorize Code.org to use Google Classroom. The first time you try syncing a section with Google Classroom, you will need to authorize Code.org to use Google Classroom. Click the link that says "To authorize Google Classroom, click here.". You should get something like this:
Assigning Values. The assignment operator = will assign a new value to your variable. This command assigned 100 to the variable size. The variable must always be on the left side. You would read this command as "size gets 100" since size is getting a new value of 100. Any old values it might have been assigned are lost forever.
Compares two values - numbers, strings, or other booleans - and returns true if they are not equal, otherwise false. "Hello" != "hello" returns true-- because the strings are slightly different. "3" != 3 returns false-- because the string 3 can be coerced into a number before comparing with 3.(see notes above about the forgiving ==). (2+1) != 3 returns false-- because the arithmetic expression ...
0. = is for assignment, == is for value comparison and === is for value and datatype comparison. So you can use == while comparing with the false. But this is not the best practice. We always uses '!' negation operator while converting true to false. var hungry = true; var foodHere = true; var eat = function() {.
Assignment (computer science) In computer programming, an assignment statement sets and/or re-sets the value stored in the storage location (s) denoted by a variable name; in other words, it copies a value into the variable. In most imperative programming languages, the assignment statement (or expression) is a fundamental construct.
While it is past the student's Sunday deadline for project submission, I wanted to offer a possible solution to this issue, should it occur again in the future. If a student finds that they are unable to unsubmit an assignment/project, have them run the code once. From a previous surfacing of this problem, that seemed to allow the Unsubmit ...
The arithmetic operators +, -, *, and / are used to perform arithmetic on a and b. For example, 3 / 2 evaluates to 1.5. Evaluates to the remainder when a is divided by b. Assume that a and b are positive integers. For example, 17 MOD 5 evaluates to 2. Evaluates to a random integer from a to b, including a and b.
Go to the unit or course overview page for the lesson you want to assign ( example unit overview page and example course overview page) Tap the the "Send to Students" button on the Lesson you want to assign in Google Classroom. Note: previously the Google Classroom button showed up here, but it is now behind the "Send to Students" button.
costanzadev • 1 yr. ago. Firstly, get the value of the gender drop down in the same way as you did with the introvert, so: gender = getText("genderDropDown"); And then, in your if statements, you only want to be checking what values vert and gender are equal to. You do not want part of your conditions being like this:
Personally, I use screenshots from the assignments and projects when I am referring to them in Nearpod. Nearpod does have the option to add a video. I could do a screen recording (Screencastify or Loom) of a Code.org assignment, especially if I wanted to emphasize the animation or something similar, and that should play within the tool. I have ...
It means you're terminating your expression in the middle of it, causing the string concatenation operators to be seen on the left-hand side of an expression (i.e. the " + 5; + bitthe semi-colon terminates the current expression, which starts a new expression with the string concatenation operator). You're also missing some quotes and string ...
No - Pair programming on Code.org, in its current state, is designed to be used by students sharing one device and working together on one device. It is primarily designed for use in K-5 courses. We don't support live collaboration between students (and/or between teachers) on one single project or puzzle, but hope to add such support in the ...
console.log("Melbourne is great".substring(0, 12)); When JS sees "Melbourne is great"(0, 12), it tries to "invoke" (call) "Melbourne is great" assuming it to be a function, and then when it sees that it is not a function, it complains of "bad invocation". points. Submitted by Gaurang Tandon. about 10 years.
What happens when a course is assigned to a section, or if I change the assignment? When you assign a course to a section of yours, this course will be the first thing students see upon signing in.
It means you are using a variable name that code.org is also using for their stuff too. I think this is a mistake made by a developer and have already opened a bug months ago. There is nothing to debug you just change the variable name you are using. For example name and location cannot be used by students.