JavaScript newbie. My code is working BUT I'm still getting this alert:
should_properly_assign_key_and_value_pair, Expected 'string' to be
'object'.
Not sure how update current code to address this issue. Any advice? Thank you!
function transformFirstAndLast(array) {
var result = '';
for (var i = 0; i < array.length; i++) {
result = (array[0] + ": " + array[array.length-1]);
return result;
}
}
console.log(transformFirstAndLast(['Kevin','Bacon','Spacey']));//Kevin : 'Spacey'
Since it is expecting a key/value pair. Create a new object and set the data.
Change
result = (array[0] + ": " + array[array.length-1]);
to
var result = {};
result[array[0]] = array[array.length-1];
return result;
It's hard to understand what your code wants to do? The current code will always return the first element and the last element in the array with a ':' in middle, regardless how many other elements in the array. Is that your intention? If yes, I think you don't need to the loop, right? just return array[0] + ':' + array[arraly.length - 1] does the job for you..
If your intention is to concatenate the elements in the array, your code need to be revised.
Related
(Stack Overflow doesn't have a tag for 'prompt' so I have used alert as I am guessing it is similar enough to attract the right answerers.)
Hello,
I am currently making a JavaScript-based game for an assignment at university. I am usually pretty good with problem solving but have been stumped by this issue.
To explain, I have an array which names the possible armour slots the player can pick. In any order these can be picked, and each time the choice gets pushed to a second array which handles what has already been picked (and in what order) and that item gets spliced from the original array. There is a while loop which runs through until all 3 have been picked.
var armourSlotToPick = ["Head", "Chest", "Legs"],
armourSlotPicked = [],
armourLoop = 1,
indexArmour = 0;
function numInArray() {
indexArmour++;
return (indexArmour + ". " + armourSlotToPick[indexArmour - 1] + "\n");
}
function armour() {
while (armourLoop < 4) {
var armourPick = prompt("Pick an armour slot to generate an item for:\n" + armourSlotToPick.forEach(numInArray));
if (armourPick == 1) {
armourSlotPicked.push(armourSlotToPick[0]);
armourSlotToPick.splice(0,1);
} else if (armourPick == 2) {
armourSlotPicked.push(armourSlotToPick[1]);
armourSlotToPick.splice(1,1);
} else if (armourPick == 3) {
armourSlotPicked.push(armourSlotToPick[2]);
armourSlotToPick.splice(2,1);
} else {
alert("Invalid choice, you suck");
break;
}
armourLoop++;
}
}
I know it probably wouldn't be possible to do the whole return in numInArray() to the prompt, but it shows some working.
Now the problem: I got it working so that each item in the array was numbered (var armourSlotToPick = ["1. Head", "2. Chest", "3. Legs"],) but as you could see, if the player chose 2, then the next time it would show "1. Head (new line) 3. Legs" and when the player chooses 3, a problem would occur, as they were really meant to choose 2. How is it possible to number the items in the array, in a prompt?
I'm possibly over thinking this but I have suffered for a few hours now.
I thank you in advance for any insight you may have,
Daniel.
EDIT: Solved.
Below is the end result, a slight variation from the edited answer from Jonathan Brooks.
var armourSlotToPick = [null, "Head", "Chest", "Legs"]
var armourSlotPicked = [null];
var armourLoop = 1;
function armour() {
while (armourLoop < 4) {
var message = "Pick an armour slot to generate an item for:\n";
for (var i = 0; i < armourSlotToPick.length; i++) {
if (armourSlotToPick[i] !== null) {
message += "" + i + ". " + armourSlotToPick[i] + "\n";
}
}
var armourPick = prompt(message);
if (armourPick > armourSlotToPick.length-1 || armourPick < 1) {
alert("Invalid choice, you suck");
} else {
var insert = armourSlotToPick.splice(armourPick, 1);
armourSlotPicked.push(insert);
}
armourLoop++;
}
armourSlotPicked.splice(0,1);
}
armour();
alert(armourSlotPicked.join("\n"));
I thank all that have contributed to this discussion and the end result, and I hope this is a good example for future problems people may have similar to this.
Check out my fiddle, I think I have a working solution.
What you really want to be using are Object Literals with your own indexing (starting from 1) - if it were me, I would create my own way to iterate over this custom indexing by adding a method to the Object's prototype, but I digress.
You're overcomplicating your code by using a while loop, and that large bulk of if statements is unnecessary: instead, all you need is some basic validation on the input and then you can just trust whatever input passes this validation. That is demonstrated here:
if ( armourPick > armourSlotToPick.length || armourPick < 1 ) {
alert("Invalid choice, you suck");
}
else {
armourSlotPicked.push( armourSlotToPick[armourPick-1] )
alert (armourSlotPicked[armourSlotPicked.length-1].value);
}
Read my code carefully, and you should get a better understanding of how to deal with certain issues.
EDIT:
As per your request, I think I have a solution that suits your needs. Basically all you have to do to have the arrays "start" at an index of 1 is to fill the zeroth element with a null value, like so:
var armourSlotToPick = [null, "Head", "Chest", "Legs"]
var armourSlotPicked = [null];
You just have to remember to take this null object into account in your code, for example:
if (armourSlotToPick[i] !== null) {
message += "" + i + "\n";
}
The indices will update automatically. See this updated fiddle for more details.
use structures / objects as content in the array, instead of just values.
the basic concept:
armourSlotPicked.push({ "key": 1, "value":armourSlotToPick[1]})
alert("value: " + armourSlotPicked[0].value)
alert("key: " + armourSlotPicked[0].key)
edit: responding to comments can take some space.
IMHO a prompt is the completely wrong tool for this, since most browsers would ask the user permission to prevent multiple popups, and since a promt can only return 1 piece of information, you can only ask for 1 thing per popup. Instead you ought to use a div element, with checkboxes for each information..
That being said it can easily be used in a promt.
The prompt is just a built in function, that takes a string as an argument (which is shown as text in the popup) and returns a string with the users input.
what does the magic for you is in fact this:
array.foreach(): The forEach() method executes a provided function once per array element.
in your case that means it calls a function that returns a string for each element in the array, and concatenates the strings.
in the old days you would have written this:
var messageText= "Pick an armour slot to generate an item for:\n"
for(var i = 1; i < armourSlotToPick.length; i++){
messageText += i + ". " + armourSlotToPick[i- 1] + "\n";
}
var armourPick = prompt(messageText);
but in this modern age, you define a printing function, and use it to generate the loop:
function numInArray() {
indexArmour++;
return (indexArmour + ". " + armourSlotToPick[indexArmour - 1] + "\n");
}
//more code before we get to where the function is used....
indexArmour = 0;
var messageText = "Pick an armour slot to generate an item for:\n" + armourSlotToPick.forEach(numInArray);
var armourPick = prompt(messageText);
or in a single line as in your code:
indexArmour = 0; //you forgot this - otherwise the list will only be complete once?
var armourPick = prompt("Pick an armour slot to generate an item for:\n" + armourSlotToPick.forEach(numInArray));
It produces the same output, because it does the same thing, its just written very differently!
If the array holds "object literals" instead of simply values, as I suggest, the old fashioned code would look something like this:
function contains(a, value) {
try{
for (var i = 0; i < a.length; i++) {
if (a[i].value == value) {
return true;
}
}
}
catch(err) {
// do nothing
};
return false;
}
and later..
for(var j = 0; j < 4; j++){
for(var i = 0; i < Math.min(armourSlotToPick.length); i++){
if( contains(armourSlotPicked, armourSlotToPick[i- 1]) )
continue;
var messageText = "Generate an item for armour in slot: " + i + "\n"
messageText += armourSlotToPick[i- 1] + "\n";
}
var armourPick = prompt(messageText);
if (armourPick > 0 && armourPick < armourSlotToPick.length) {
armourSlotPicked.push({"key":j, "value":armourSlotToPick[armourPick]);
}
...
}
//now we have an array that holds information about when what was picked..
or something along those lines.. this is bt.w completely untested, it's just for illustration
You want to use the array index to number your items. Since your numbers are one-based and the index is zero-based, you will need to convert between the two when outputting and interpreting the response.
This approach will also allow you to eliminate all but two of the cases in your if-else statement.
I'm trying to dynamically find a particular value inside a multi dimensional object.
To create the object, I'm doing this:
var inViewElements = {};
$('.story-section')
.each(
function(index){
var sectionId = 'story-section-' + Math.floor(Math.random() * (1000 - 1 + 1)) + 1;
$(this).attr('id', sectionId);
var inViewHeight = $(this).height(),
inViewPosTop = $('#' + sectionId).offset().top,
inViewPosBottom = ((inViewPosTop + inViewHeight) - (inViewTolerence + inViewHeight));
inViewElements[inViewPosTop] = {
id: sectionId,
height: inViewHeight,
bottom: inViewPosBottom
};
debug('Inview', 'Object', sectionId);
debug('Inview', 'Height', inViewHeight);
debug('Inview', 'Offset Top', inViewPosTop);
debug('Inview', 'Offset Bottom', inViewPosBottom);
}
);
console.log(inViewElements);
And the output looks like:
What I'm trying to do is compare if another variable value, for example:
var currentPos = '3038';
Matches any of the objects keys. E.g. the 3038 or 2038 etc.
I'm struggling to figure this one out!
So you're trying to search for an object that contains a certain value?
There is no way to query an array/object in Javascript. As you're not using incremental indexes, I would suggest using a foreach loop, using a conditional statement to check whether the property you're trying to match is equal to the value you're looking for.
It would be quicker to use a for loop, however that would require incremental indexes.
If you r logging response variable through which ur output came then u can use this function
for(var x in response){
if( x == 3038) {
// do something
}
}
or
for(var x in response){
if(x == currentPos){
//dosomething
}
}
can u give me the proper code of how u put values to console log so i will edit the answer properly accourding to your question
Lately I've been having trouble checking whether an input (player name) has been input more than once. This is not in-database, but just based on arrays contained within JavaScript. What I've been using after a couple of google searches was the indexOf() function. However this does not seem to work. My code is as follows:
var numberPlayers = 1;
var players = [];
var AddPlayer = function() {
if(!(players.indexOf($(".name")).val() > -1)) {
players.push($(".name").val());
$(".players").append("<p>Player number " + numberPlayers + " is " + $(".name").val() + "</p>");
numberPlayers++;
}
};
What method of detection would you recommend? I've tried looping, but wouldn't work either.
EDIT: Updated code. Still doesn't work!
Try this - note where the ) is placed:
if(!(players.indexOf($(".name").val()) > -1)) {
instead of:
if(!(players.indexOf($(".name")).val() > -1)) {
and actually, for readability this would be better:
var name = $('.name').val();
if ( players.indexOf(name) == -1)) {
In general, try adding console.log and breakpoints to find your bugs...
You can use an object (read Set / Hash) instead of an array; it should be faster anyway.
Note that I'm also using .text() which will escape text.
var numberPlayers = 1;
var players = {};
var AddPlayer = function() {
var newPlayer = $(".name").val();
if(!(newPlayer in players)) {
players[newPlayer] = true;
$(".players").append($("<p>").text("Player number " + numberPlayers + " is " + newPlayer));
numberPlayers++;
}
};
jQuery has a utility function for this:
$.inArray(value, array)
It returns the index of a value in an array. It returns -1 if the array does not contain the value.
for(var i = 0; i < this.phrases.length; i++) {
console.log('sort ' + this.phrases[i]);
console.log('sort length' + this.phrases.length);
if(this.phrases[i] == null) {
var s = this.phrases.splice(i, 1);
console.log('splice ' + this.phrases[i]);
console.log('splice length ' + this.phrases.length);
}
}
I have an array (this.phrases). I made the phrase that I want to remove equal to null in another section. The first log prints null, the second log also prints null. Why is it not getting spliced? This is also sometimes the last item in an array. Are you not able to splice an array with only one element? The same thing happens, however if it is not the last item in this.phrases.
Edit: s also does not seem to get set to any value.
Edit: The two length logs I added print the same number.
Edit: That's not actually true. Weird things are happening with the lengths, probably not involving this section of code. I just want to know if I'm using splice() correctly.
Switch these two lines:
var s = this.phrases.splice(i,1);
console.log('splice ' + this.phrases[i]);
To this:
console.log('splice ' + this.phrases[i]);
this.phrases.splice(i, 1);
i--;
const indexOfValue = treeSelectDataTemp.findIndex((item: any) => item.value === deleteIndexId[d]);
console.log(" ########### deleted indexOfValue ", indexOfValue);
if (indexOfValue !== -1) {
treeSelectDataTemp.splice(indexOfValue, 1);
}
Okay, so what I have is basically three dynamic drop down boxes and a 2D array. I have each box adding their values together, and then I want the sum of the values to be searched for through the array to pull out the fifth value on whatever the row the value was on.
var shape = document.getElementById("shape").value;
var dimension_one = document.getElementById("dimension_One").value;
var x = 'x';
var dimension_two = document.getElementById("dimension_Two").value;
var selected_beam = shape + dimension_one + x + dimension_two; // combine all values from text boxes
alert(selected_beam);
for (i = 0; i < array_shapes.length; i++)
{
if (array_shapes[i][2] == selected_beam) {
alert('Area=' + array_shapes[i][5]);
//Area= array_shapes[i][5]);
}
}
I know that selected _beam is giving me the value I want, and I also know that the array loop returns what I want out of the array but only if I replace
if (array_shapes[i][2] == selected_beam)
with
if (array_shapes[i][2] == "value I want to search for")
So what I really need to know is - why will it only accept it as a string and not as my selected_beam variable.
Based on your array values, it looks like you need var x to be uppercase like:
var x = 'X';
If I am reading your array correctly, it also looks like the beam size is in element 0 and 1 of the array not 1 and 2, so you may need to not look for array_shapes[i][2], but rather array_shapes[i][0] or array_shapes[i][1]
The first item in the array is at index value = 0.
You need to do some debugging.
To start off, you need to know why selected_beam !== "your value".
I suggest you use this function to compare the strings:
function compare( s1, s2 ){
alert("s1: " + s1.toString());
alert("s2: " + s2.toString());
if (s1.toString() == s2.toString())
return alert("true");
return alert("false");
}
>>> compare(selected_beam,"your value");
The problem might be as simple as having unnecessary characters in your selected_beam.
So where you have alert(selected_beam), try to compare the strings and see if it returns true or false.
You are concatenating values that you're parsing from a text box. The result will be a string
Try doing:
var selected_beam = parseInt(shape) + parseInt(dimension_one) + parseInt(x) + parseInt(dimension_two);