Develop Reference

$.when apply for single request

I am trying to use $.when apply in my code. However, it seems that the format return is different for single and multiple request. How can i cater for it?? I am trying not to have another if else outside of it.
$.when.apply(null, apiRequestList).then(function () {
for (var i = 0; i < arguments.length; i++) {
var value = arguments[0];
}
});
This is what i do not want to do.
if (apiRequestList.length === 1) {
$.ajax({
});
} else {
$.when.apply(null, apiRequestList).then(function () {
for (var i = 0; i < arguments.length; i++) {
var value = arguments[0];
}
});
}

You can simply convert arguments into an array, when the length of apiRequestList is 1:
$.when.apply(null, apiRequestList).then(function() {
var _arguments = Array.prototype.slice.call(arguments);
if (Array.isArray(apiRequestList) && apiRequestList.length === 1)
_arguments = [arguments];
for (var i = 0; i < _arguments.length; i++) {
var value = _arguments[i][0];
console.log(value);
}
});
Live Example on jsFiddle (since we can't do ajax on Stack Snippets):
function x(a) {
return $.post("/echo/html/", {
html: "a = " + a,
delay: Math.random()
});
}
function doIt(apiRequestList) {
$.when.apply(null, apiRequestList).then(function() {
var _arguments = arguments;
if (Array.isArray(apiRequestList) && apiRequestList.length === 1)
_arguments = [arguments];
for (var i = 0; i < _arguments.length; i++) {
var value = _arguments[i][0];
console.log(value);
}
console.log("----");
});
}
doIt([x(1), x(2), x(3)]);
doIt([x(4)]);
Example output (it'll vary because of the Math.random()):
a = 4
----
a = 1
a = 2
a = 3
----

creating a new array out of an object

I've created a JavaScript object to get the number of times a character repeats in a string:
function getFrequency(string) {
// var newValsArray =[];
var freq = {};
for (var i=0; i<string.length;i++) {
var character = string.charAt(i);
if (freq[character]) {
freq[character]++;
} else {
freq[character] = 1;
}
}
return freq;
}
Now, I'm trying to construct a new string composed of the keys & their properties (the letters) & numbers of times the letters repeat if the number (property) is more than one but I keep getting undefined and I don't know why:
function newString(freq){
var newValsArray = [];
for (var prop in freq) {
if (freq[prop]>1){
newValsArray.push(prop + freq[prop]);
}
else if (freq[prop] < 2){
newValsArray.push(prop);
}
}
return newValsArray;
}
I feel like my syntax is off or something... if anyone has any suggestions, I'd really appreciate it...

You aren't explicitly returning anything from newString(), so it will return undefined. It sounds like you want something like this:
return newValsArray.join('');
at the end of newString() to construct an actual string (instead of returning an array). With that change, newString(getFrequency("Hello there") will return 'He3l2o thr'.

function getFrequency(string) {
// var newValsArray =[];
var freq = {};
for (var i = 0; i < string.length; i++) {
var character = string.charAt(i);
if (freq[character]) {
freq[character] ++;
} else {
freq[character] = 1;
}
}
return freq;
}
function newString(freq) {
var newValsArray = [];
for (var prop in freq) {
if (freq[prop] > 1) {
newValsArray.push(prop + freq[prop]);
} else if (freq[prop] < 2) {
newValsArray.push(prop);
}
}
return newValsArray.join("");
}
var mystring = "Here are some letters to see if we have any freq matches and so on.";
var results = newString(getFrequency(mystring));
var elem = document.getElementById("results");
elem.innerHTML = results;
<div id="results"></div>

You are not returning anything from the newString function. Add return newString; as the last line of the newString function. Adding that line does result in something being returned, though I can't tell if it is what you expected.
var text = "asdfjhwqe fj asdj qwe hlsad f jasdfj asdf alhwe sajfdhsadfjhwejr";
var myFreq = getFrequency(text);
show(myFreq);
var myNewValsArray = newString(myFreq);
show(myNewValsArray);
function getFrequency(string) {
// var newValsArray =[];
var freq = {};
for (var i=0; i<string.length;i++) {
var character = string.charAt(i);
if (freq[character]) {
freq[character]++;
} else {
freq[character] = 1;
}
}
return freq;
}
function newString(freq){
var newValsArray = [];
for (var prop in freq) {
if (freq[prop]>1){
newValsArray.push(prop + freq[prop]);
}
else if (freq[prop] < 2){
newValsArray.push(prop);
}
}
return newValsArray; // ******** ADD THIS LINE
}
function show(msg) {
document.write("<pre>" + JSON.stringify(msg, null, 2) + "</pre>");
}

Javascript sort array of objects not executing

I have to sort an array of objects and I've written the code but it just doesn't execute. The array is the same and when I look in my debugger console it jumps right to the next function and doesn't execute my sort. I've tried many things but nothing seems to work. Maybe I'm overlooking something but I hope someone knows why it doesn't execute.
My code:
function orderData(toSort) {
console.dir(toSort);
toSort.sort(compareCountries);
console.dir(toSort);
return toSort;
}
function compareCountries(a, b) {
var avgx = 0;
var avgy = 0;
avgx = calcAvgForAllProperties(a, avgx);
avgy = calcAvgForAllProperties(b, avgy);
a["overalAvg"] = avgx;
b["overalAvg"] = avgy;
if (a.overalAvg > b.overalAvg)
return -1;
else if (b.overalAvg < a.overalAvg)
return 1;
else
return 0;
}
or:
function orderData(toSort) {
console.dir(toSort);
toSort.sort(function (a, b) {
var avgx = 0;
var avgy = 0;
avgx = calcAvgForAllProperties(a, avgx);
avgy = calcAvgForAllProperties(b, avgy);
a["overalAvg"] = avgx;
b["overalAvg"] = avgy;
if (a.overalAvg > b.overalAvg)
return -1;
else if (b.overalAvg < a.overalAvg)
return 1;
else
return 0;
});
console.dir(toSort);
return toSort;
}
//EDIT
Here's an example of my data:

There are several issues with your code:
The sorting function has side effects
You should not calculate overallAvg in compareCountries. Instead, you should do this before sorting.
var countries = [ /* your countries */ ];
countries.forEach(calculateCountryOverallFooAverage); // Standard forEach is not chainable.
countries.sort(compareCountriesByOverallFooAverage);
function calculateCountryOverallFooAverage(country) {
country.calculateOverallFooAverage();
}
function compareCountriesByOverallFooAverage(lhs, rhs) {
var lhsAvg = lhs.overallFooAverage();
var rhsAvg = rhs.overallFooAverage();
if (lhsAvg < rhsAvg) { return -1; }
else if(lhsAvg > rhsAvg) { return 1; }
return 0;
}
The comparison is incorrect, because the second test is equivalent with the first one (you do if (a < b) {} else if (b > a) {} else {}). It should be:
if (a.overalAvg > b.overalAvg) return -1;
else if (a.overalAvg < b.overalAvg) return 1;
else return 0;

display the recursion line by line

I am trying to make a function in javascript that would expand/split a string with dashes and show the process ( line by line ) using recursion.
for example, the string "anna" would become:
expand("anna") = expand("an")+"---"+expand("na") ->
"a"+"---"+"n"+"---"+"n"+"---"+"a"
and the desired output would be:
anna
an---na
a---n---n---a
I have achieved doing the following so far (I know it might not be the solution I am looking):
expand("anna") = an+"---"+expand("na")
= an+"---"+n+"---"+expand("a");
= an+"---"+n+"---+"a"
the output I am getting is:
an---n---a
I can't seem to concatenate the head though to do the first example.
My javascript function of expand is as follows:
function expand(word) {
if (word.length<=1) {
return word;
} else {
mid = word.length/2;
return word.substr(0,mid) + " " + expand(word.substr(mid,word.length));
}
}
document.write(expand("anna"));
I would need some tips to do this, otherwise (if it's the wrong stackexchange forum), please guide me where to post it.

this is my crazy attempt
var Word = function(str) {
this.isSplitable = function() {
return str.length > 1;
}
this.split = function() {
var p = Math.floor(str.length / 2);
return [
new Word(str.substr(0,p)),
new Word(str.substr(p,p+1))
];
}
this.toString = function() {
return str;
}
}
var expand = function(words) {
var nwords = [];
var do_recur = false;
words.forEach(function(word){
if(word.isSplitable()) {
var splitted = word.split();
nwords.push(splitted[0]);
nwords.push(splitted[1]);
do_recur = true;
}else{
nwords.push(word);
}
});
var result = [];
nwords.forEach(function(word){
result.push( word.toString() );
});
var result = result.join("--") + "<br/>";
if(do_recur) {
return result + expand(nwords);
}else{
return "";
}
}
document.write( expand([new Word("anna")]) );

This is what you need
expand = function(word) {
return [].map.call(word, function(x) {return x+'---'}).join('')
};
The joy of functional programming.
And with added code to deal with last character:
function expand(word) {
return [].map.call(word, function(x, idx) {
if (idx < word.length - 1)
return x+'---';
else return x
}).join('')
}

As I said that it is impossible to display the "process" steps of recursion while using recursion, here is a workaround that will output your desired steps:
var levels = [];
function expand(word, level) {
if (typeof level === 'undefined') {
level = 0;
}
if (!levels[level]) {
levels[level] = [];
}
levels[level].push(word);
if (word.length <= 1) {
return word;
} else {
var mid = Math.ceil(word.length/2);
return expand(word.substr(0, mid), level+1) + '---' + expand(word.substr(mid), level+1);
}
}
expand('anna');
for (var i = 0; i < levels.length; i++) {
console.log(levels[i].join('---'));
}

to see all steps the best that I whold do is:
function expand(word) {
if (word.length<=1) {
return word;
} else {
var mid = word.length/2;
var str1 = word.substr(0,mid);
var str2 = word.substr(mid,word.length);
document.write(str1 + "---" + str2 + "<br></br>");
return expand(str1) + "---" + expand(str2);
}
}
document.write(expand("anna"));

You have to return the two parts of the string:
function expand(word) {
output="";
if (word.length<=1) {
output+=word;
return output;
} else
{
var mid = word.length/2;
output+=word.substr(0,mid)+"---"+word.substr(mid)+" \n";//this line will show the steps.
output+=expand(word.substr(0,mid))+"---"+expand(word.substr(mid,word.length-1))+" \n";
return output;
}
}
console.log(expand("anna"));
Edit:
I added the output var and in every loop I concatenate the new output to it.
It should do the trick.

Hope the problem is in your first part. According to your algorithm, you are splitting your string anna in to two parts,
an & na
so you need to expand both parts until the part length is less than or equal to one. so your required function is the below one.
function expand(word) {
if (word.length<=1) {
return word;
} else {
mid = word.length/2;
return expand(word.substr(0,mid)) + " --- " + expand(word.substr(mid,word.length));
}
}
document.write(expand("anna"));

My javascript crashes the server

Now before everyone is helpful (seriously, you guys are awesome) I am doing a coding challenge that means I can't get code from other users/people. This does not, however, extend to advice so I wanted to know why my code crashes google chrome. I don't want am not allowed any code so please just point me in the right direction. I am sorry for such an odd request but I am at my wit's end.
http://jsfiddle.net/clarinetking/c49mutqw/9/
var chars;
var keyword = [];
var cipher;
var done = false;
var list1 = [];
var list2 = [];
var list3 = [];
var list4 = [];
var list5 = [];
var keylngth = 0;
$('#apnd').click(function () {
cipher = $('#Input').val();
chars = cipher.split('');
$('#Output').append(chars);
});
$('#key').click(function () {
while (done === false) {
var letter = prompt('insert letter, xyz to close');
keylngth++;
if (letter == 'xyz') {
done = true;
} else {
//Push letter to keyword array
keyword.push(letter);
}
}
});
$('#list').click(function () {
for (i = 0; i < chars.length; i++) {
var x = 1;
for (i = 1; i < keylngth+1; i++) {
if (i/x === 1) {
list1.push(chars[x]);
}
if (i/x === 2) {
list1.push(chars[x]);
}
if (i/x === 3) {
list1.push(chars[x]);
}
if (i/x === 4) {
list1.push(chars[x]);
}
if (i/x === 5) {
list1.push(chars[x]);
}
if (i/x === 6) {
list1.push(chars[x]);
}
if (i/x === 7) {
list1.push(chars[x]);
}
if (i/x === 8) {
list1.push(chars[x]);
}
}
x++;
}
alert(list1);
alert(list2);
});
I apologize to all you coders out there that are probably screaming at me USE A REPEAT LOOP! but for the list function I see no way to. As previously mentioned, no code please unless it's pseudo code :)

In your $('#list').click(function ()) function you are running an infinite for bucle, it's because you use the same i counter for the two for bucles so you javascript will run forerver and crash the browser