We Keep Coding

Join rest of the elements of an array with the first element

I'm trying the following logic and not sure which array function can help. I'm not able to use map or es6 but would like to see an answer.
I tried the following:
/* JS */ - This is not working and would like to see how to make it work.
var input = ['x','y','z'];
var powerSetResult = powerSet(input);
console.log(powerSetResult);
/*Ouput should be [''.'x','y','z','xy,'xz','yz','xyz']*/
function powerSet(arr) {
var data = [];
for(var i=0; i<arr.length; i++) {
arr[i] = arr[i] + arr[i+1];
data.push(arr[i]);
}
console.log(data);
return data;
}
/* ES 6 */ - Is there a better way to do this?
let input = ['x','y','z'];
let powerSetResult = powerSet(input);
console.log(powerSetResult);
/*Ouput should be [''.'x','y','z','xy,'xz','yz','xyz']*/
const powerSet(arr) {
let data = arr.map(([s1, s2, s3]) => [``,`${s1}`,`${s2}`,`${s3}`,`${s1}${s2}`,`${s1}${s3}`,`${s2}${s3}`,`${s1}${s2}${s3}`]);
console.log(data);
return data;
}

Certainly not the most efficient... but you could do this:
var input = ['x','y','z'];
var powerSetResult = powerSet(input);
console.log(powerSetResult);
function powerSet(arr, result) {
result = result || new Set();
const str = arr.join('');
for (let i = 0; i < arr.length; i++) {
for (let j = i; j <= arr.length; j++) {
result.add(str.slice(i, j));
}
powerSet([...arr.slice(0, i), ...arr.slice(i+1)], result)
}
return Array.from(result).sort((a, b) => {
return (a.length - b.length) || a.localeCompare(b);
});
}
/* Output should be [''.'x','y','z','xy,'xz','yz','xyz'] */
Caveat being it will only work for single letter elements, but is easily modifiable to accommodate more.

Sort array of strings into array of objects

Okay, so I've been working on a sort function for my application, and I've gotten stuck.
Here's my fiddle.
To explain briefly, this code starts with an array of strings, serials, and an empty array, displaySerials:
var serials = ["BHU-009", "BHU-008", "BHU-001", "BHU-010", "BHU-002", "TYU-970", "BHU-011", "TYU-969", "BHU-000"];
var displaySerials = [];
The aim of these functions is to output displaySerials as an array of objects with two properties: beginSerial and endSerial. The way that this is intended to work is that the function loops through the array, and tries to set each compatible string in a range with each other, and then from that range create the object where beginSerial is the lowest serial number in range and endSerial is the highest in range.
To clarify, all serials in a contiguous range will have the same prefix. Once that prefix is established then the strings are broken apart from the prefix and compared and sorted numerically.
So based on that, the desired output from the array serials would be:
displaySerials = [
{ beginSerial: "BHU-008", endSerial: "BHU-011" },
{ beginSerial: "BHU-000", endSerial: "BHU-002" },
{ beginSerial: "TYU-969", endSerial: "TYU-970" }
]
I've got it mostly working on my jsfiddle, the only problem is that the function is pushing one duplicate object into the array, and I'm not sure how it is managing to pass my checks.
Any help would be greatly appreciated.

Marc's solution is correct, but I couldn't help thinking it was too much code. This is doing exactly the same thing, starting with sort(), but then using reduce() for a more elegant look.
var serials = ["BHU-009", "BHU-008", "BHU-001", "BHU-010", "BHU-002", "TYU-970", "BHU-011", "TYU-969", "BHU-000"]
serials.sort()
var first = serials.shift()
var ranges = [{begin: first, end: first}]
serials.reduce(mergeRange, ranges[0])
console.log(ranges) // the expected result
// and this is the reduce callback:
function mergeRange(lastRange, s)
{
var parts = s.split(/-/)
var lastParts = lastRange.end.split(/-/)
if (parts[0] === lastParts[0] && parts[1]-1 === +lastParts[1]) {
lastRange.end = s
return lastRange
} else {
var newRange = {begin: s, end: s}
ranges.push(newRange)
return newRange
}
}
I've got a feeling that it's possible to do it without sorting, by recursively merging the results obtained over small pieces of the array (compare elements two by two, then merge results two by two, and so on until you have a single result array). The code wouldn't look terribly nice, but it would scale better and could be done in parallel.

Nothing too sophisticated here, but it should do the trick. Note that I'm sorting the array from the get-go so I can reliably iterate over it.
Fiddle is here: http://jsfiddle.net/qyys9vw1/
var serials = ["BHU-009", "BHU-008", "BHU-001", "BHU-010", "BHU-002", "TYU-970", "BHU-011", "TYU-969", "BHU-000"];
var myNewObjectArray = [];
var sortedSerials = serials.sort();
//seed the object
var myObject = {};
var previous = sortedSerials[0];
var previousPrefix = previous.split("-")[0];
var previousValue = previous.split("-")[1];
myObject.beginSerial = previous;
myObject.endSerial = previous;
//iterate watching for breaks in the sequence
for (var i=1; i < sortedSerials.length; i++) {
var current = sortedSerials[i];
console.log(current);
var currentPrefix = current.split("-")[0];
var currentValue = current.split("-")[1];
if (currentPrefix === previousPrefix && parseInt(currentValue) === parseInt(previousValue)+1) {
//sequential value found, so update the endSerial with it
myObject.endSerial = current;
previous = current;
previousPrefix = currentPrefix;
previousValue = currentValue;
} else {
//sequence broken; push the object
console.log(currentPrefix, previousPrefix, parseInt(currentValue), parseInt(previousValue)+1);
myNewObjectArray.push(myObject);
//re-seed a new object
previous = current;
previousPrefix = currentPrefix;
previousValue = currentValue;
myObject = {};
myObject.beginSerial = current;
myObject.endSerial = current;
}
}
myNewObjectArray.push(myObject); //one final push
console.log(myNewObjectArray);

I would use underscore.js for this
var bSerialExists = _.findWhere(displaySerials, { beginSerial: displaySettings.beginSerial });
var eSerialExists = _.findWhere(displaySerials, { endSerial: displaySettings.endSerial });
if (!bSerialExists && !eSerialExists)
displaySerials.push(displaySettings);

I ended up solving my own problem because I was much closer than I thought I was. I included a final sort to get rid of duplicate objects after the initial sort was finished.
var serials = ["BHU-009", "BHU-008", "BHU-001", "BHU-010", "BHU-002", "TYU-970", "BHU-011", "TYU-969", "BHU-000"];
var displaySerials = [];
var mapSerialsForDisplay = function () {
var tempArray = serials;
displaySerials = [];
for (var i = 0; i < tempArray.length; i++) {
// compare current member to all other members for similarity
var currentSerial = tempArray[i];
var range = [currentSerial];
var displaySettings = {
beginSerial: currentSerial,
endSerial: ""
}
for (var j = 0; j < tempArray.length; j++) {
if (i === j) {
continue;
} else {
var stringInCommon = "";
var comparingSerial = tempArray[j];
for (var n = 0; n < currentSerial.length; n++) {
if (currentSerial[n] === comparingSerial[n]) {
stringInCommon += currentSerial[n];
continue;
} else {
var currentRemaining = currentSerial.replace(stringInCommon, "");
var comparingRemaining = comparingSerial.replace(stringInCommon, "");
if (!isNaN(currentRemaining) && !isNaN(comparingRemaining) && stringInCommon !== "") {
range = compareAndAddToRange(comparingSerial, stringInCommon, range);
displaySettings.beginSerial = range[0];
displaySettings.endSerial = range[range.length - 1];
var existsAlready = false;
for (var l = 0; l < displaySerials.length; l++) {
if (displaySerials[l].beginSerial == displaySettings.beginSerial || displaySerials[l].endSerial == displaySettings.endSerial) {
existsAlready = true;
}
}
if (!existsAlready) {
displaySerials.push(displaySettings);
}
}
}
}
}
}
}
for (var i = 0; i < displaySerials.length; i++) {
for (var j = 0; j < displaySerials.length; j++) {
if (i === j) {
continue;
} else {
if (displaySerials[i].beginSerial === displaySerials[j].beginSerial && displaySerials[i].endSerial === displaySerials[j].endSerial) {
displaySerials.splice(j, 1);
}
}
}
}
return displaySerials;
}
var compareAndAddToRange = function (candidate, commonString, arr) {
var tempArray = [];
for (var i = 0; i < arr.length; i++) {
tempArray.push({
value: arr[i],
number: parseInt(arr[i].replace(commonString, ""))
});
}
tempArray.sort(function(a, b) {
return (a.number > b.number) ? 1 : ((b.number > a.number) ? -1 : 0);
});
var newSerial = {
value: candidate,
number: candidate.replace(commonString, "")
}
if (tempArray.indexOf(newSerial) === -1) {
if (tempArray[0].number - newSerial.number === 1) {
tempArray.unshift(newSerial)
} else if (newSerial.number - tempArray[tempArray.length - 1].number === 1) {
tempArray.push(newSerial);
}
}
for (var i = 0; i < tempArray.length; i++) {
arr[i] = tempArray[i].value;
}
arr.sort();
return arr;
}
mapSerialsForDisplay();
console.log(displaySerials);
fiddle to see it work

Here's a function that does this in plain JavaScript.
var serials = ["BHU-009", "BHU-008", "BHU-001", "BHU-010", "BHU-002", "TYU-970", "BHU-011", "TYU-969", "BHU-000"];
function transformSerials(a) {
var result = []; //store array for result
var holder = {}; //create a temporary object
//loop the input array and group by prefix
a.forEach(function(val) {
var parts = val.split('-');
var type = parts[0];
var int = parseInt(parts[1], 10);
if (!holder[type])
holder[type] = { prefix : type, values : [] };
holder[type].values.push({ name : val, value : int });
});
//interate through the temp object and find continuous values
for(var type in holder) {
var last = null;
var groupHolder = {};
//sort the values by integer
var numbers = holder[type].values.sort(function(a,b) {
return parseInt(a.value, 10) > parseInt(b.value, 10);
});
numbers.forEach(function(value, index) {
if (!groupHolder.beginSerial)
groupHolder.beginSerial = value.name;
if (!last || value.value === last + 1) {
last = value.value;
groupHolder.endSerial = value.name;
if (index === numbers.length - 1) {
result.push(groupHolder);
}
}
else {
result.push(groupHolder);
groupHolder = {};
last = null;
}
});
}
return result;
}
console.log(transformSerials(serials));
<script src="http://gh-canon.github.io/stack-snippet-console/console.min.js"></script>

removing multiple arrays from a 2D array

My web app is taking in arbitrarily large 2D arrays that sometimes look something like this:
var multiArray = [["","","",""],[1,2,3],["hello","dog","cat"],["","","",""]];
I want to write a function to take out every array inside of multiArray that is comprised entirely of quotes. In other words, any array that looks like this:
["","","",""]
should be deleted from multiArray.
I tried writing the following function, but the problem with using splice in a for loop is that splicing will change the length of the array, and I end up trying to access undefined elements. Please help!
Thanks!
Here's the incorrect function I wrote:
function cleanWhitespace(arrayOfArrays) {
var i;
var arrayOfArraysLength = arrayOfArrays.length;
for (i = 0; i < arrayOfArraysLength; i++) {
var cleanedArray = $.grep(arrayOfArrays[i], function(element) {
return element != ""
});
if (cleanedArray.length == 0) {
arrayOfArrays.splice(i, 1);
}
}
return arrayOfArrays;
};

You can use $.grep :
multiArray = $.grep(multiArray, function(v){
return v.join('');
});
Fiddle : http://jsfiddle.net/scZcB/

on the fly:
var multiArray = [["","","",""],[1,2,3],["hello","dog","cat"],["","","",""]];
var outputArr = removeQuoteArrays(multiArray);
console.log(outputArr);
function removeQuoteArrays(arr) {
var outputArr = [];
for (var i = 0; i < arr.length; i++) {
var currArr = arr[i];
var isAllQuotes = true;
for (var j = 0; j < currArr.length; j++) {
if (currArr[j] != "") {
isAllQuotes = false;
break;
}
}
if (!isAllQuotes) {
outputArr.push(currArr);
}
}
return outputArr;
}
Here's a JSFiddle.

Create a new array instead.
// Only add if...
cleanedArray = multiArray.filter(function(arr){
// Some elements are not blank
return arr.some(function(e){ return e !== "" })
})

I added a length check to your function to break out of the loop if the index reaches the array length:
if (i >= arrayOfArrays.length)
break;
Which makes:
function cleanWhitespace(arrayOfArrays) {
var i;
var arrayOfArraysLength = arrayOfArrays.length;
for (i = 0; i < arrayOfArraysLength; i++) {
var cleanedArray = $.grep(arrayOfArrays[i], function(element) {
return element != ""
});
if (cleanedArray.length == 0) {
arrayOfArrays.splice(i, 1);
if (i >= arrayOfArrays.length)
break;
}
}
return arrayOfArrays;
};

var multiArray = [["","","",""],[1,2,3],["hello","dog","cat"],["","","",""]];
function cleanWhitespace(arrayOfArrays) {
for (var i = 0; i < arrayOfArrays.length; i++) {
var emptyElements = 0;
for (var j = 0; j < arrayOfArrays[i].length; j++ ) {
if (arrayOfArrays[i][j] === "") {
emptyElements++;
}
}
if (emptyElements === arrayOfArrays[i].length) {
arrayOfArrays.splice(i, 1);
}
}
return arrayOfArrays;
}
console.log(cleanWhitespace(multiArray));
http://jsfiddle.net/4Jfr9/

Array length undefined after split

I'd like to split a string ("1,2,3") and return it as an int array so I wrote the following function:
function stringToIntArray(string) {
var split = {};
split = string.split(',');
var selected = {};
for (var i = 0; i <= split.length; i++) {
selected[i] = split[i];
}
return selected;
}
However split.length is always undefinied. Where's my mistake?

var selected = {};
doesn't build an array but an object, which has no length property.
You can fix your code by replacing it with
var selected = [];
If you want to return an array of numbers, you can change your code to
function stringToIntArray(string) {
var split = string.split(',');
var selected = [];
for (var i = 0; i < split.length; i++) {
selected.push(parseInt(split[i], 10));
}
return selected;
}
Note that I replaced <= with < in your loop.
Note also that for modern browsers, you can use the map function to make it simpler :
function stringToIntArray(string) {
return string.split(',').map(function(v){ return parseInt(v, 10) });
}

how can I parse json with multiple lines

I have the following JSON:
[{"returnCode":"0","errorMessage":"success","Code":{},"phoneNumber":"400557704","mobile":"400089151"},
{"returnCode":"0","errorMessage":"success","Code":{},"phoneNumber":"400557705","mobile":"400089151"},
{"returnCode":"0","errorMessage":"success","Code":{},"phoneNumber":"400557706","mobile":"400089151"},
{"returnCode":"0","errorMessage":"success","Code":{},"phoneNumber":"400557707","mobile":"400089151"}]
I need to extract all "phoneNumber" using a js function.
I'm testing from using html and my function is not so good:
function getNumbers(strJSON)
{
strJSON = "[{\"errorMessage\":\"success\",\"mobile\":\"400089151\",\"phoneNumber\":\"400557704\",\"returnCode\":\"0\"},{\"errorMessage\":\"success\",\"mobile\":\"400089151\",\"phoneNumber\":\"400557705\",\"returnCode\":\"0\"},{\"errorMessage\":\"success\",\"mobile\":\"400089151\",\"phoneNumber\":\"400557706\",\"returnCode\":\"0\"}]";
var len = strJSON.length;
var begin_index = strJSON.indexOf("returnCode") - 2;
var last_index = len - 1;
var string_toSplit = strJSON.substring(begin_index, last_index);
var string_splitted = string_toSplit.split("{");
var out="";
alert(strJSON);
alert("string_splitted");
alert(string_splitted);
for ( var i = 0; i < string_splitted.length; i++)
{
if (string_splitted[i].charAt(string_splitted[i].length - 1) === ",")
{
string_splitted[i] = string_splitted[i].slice(0, -1);
}
var json = "{" + string_splitted[i];
var obj = JSON.parse(json);
if (i == string_splitted.length)
{
out = out + obj.phoneNumber;
}
else
{
out = out + obj.phoneNumber + ",";
}
}
return out;
}

For modern browsers you can use the .map() method
var j = [{"returnCode":"0","errorMessage":"success","Code":{},"phoneNumber":"400557704","mobile":"400089151"},
{"returnCode":"0","errorMessage":"success","Code":{},"phoneNumber":"400557705","mobile":"400089151"},
{"returnCode":"0","errorMessage":"success","Code":{},"phoneNumber":"400557706","mobile":"400089151"},
{"returnCode":"0","errorMessage":"success","Code":{},"phoneNumber":"400557707","mobile":"400089151"}];
var phones = j.map(function(item){return item.phoneNumber});
Update
After seeing your code (do not try to manually split/parse the json string.. use the JSON.parse method) you should use
function getNumbers(strJSON)
{
var myJson = JSON.parse( strJSON );
return myJson.map(function( item ){ return item.phoneNumber}).join(',');
}

Update: An even better way:
function getNumbers(strJSON)
{
var obj = JSON.parse(strJSON);
return obj.map(x => x.phoneNumber).join(", ")
}
Original Post:
A straight forward method is to just iterate over every object in the array and take the values out individually.
var info = [{"returnCode":"0","errorMessage":"success","Code":{},"phoneNumber":"400557704","mobile":"400089151"},
{"returnCode":"0","errorMessage":"success","Code":{},"phoneNumber":"400557705","mobile":"400089151"},
{"returnCode":"0","errorMessage":"success","Code":{},"phoneNumber":"400557706","mobile":"400089151"},
{"returnCode":"0","errorMessage":"success","Code":{},"phoneNumber":"400557707","mobile":"400089151"}];
var phoneNumbers = [];
for (var i = 0; i < info.length; i++)
{
phoneNumbers.push(info[i].phoneNumber);
}
console.log(phoneNumbers);
http://jsfiddle.net/hX69r/
UPDATE:
http://jsfiddle.net/hX69r/1/
var info = [{"returnCode":"0","errorMessage":"success","Code":{},"phoneNumber":"400557704","mobile":"400089151"},
{"returnCode":"0","errorMessage":"success","Code":{},"phoneNumber":"400557705","mobile":"400089151"},
{"returnCode":"0","errorMessage":"success","Code":{},"phoneNumber":"400557706","mobile":"400089151"},
{"returnCode":"0","errorMessage":"success","Code":{},"phoneNumber":"400557707","mobile":"400089151"}];
var infoString = JSON.stringify(info); //this just turns the object array 'info' into a string
var numbers = getNumbers(infoString);
console.log(numbers);
function getNumbers(strJSON)
{
var obj = JSON.parse(strJSON);
var phoneNumbers = [];
for (var i = 0; i < obj.length; i++)
{
phoneNumbers.push(obj[i].phoneNumber);
}
return phoneNumbers.join(", ");
}
Additional Update:
var info = [{"returnCode":"0","errorMessage":"success","Code":{},"phoneNumber":"400557704","mobile":"400089151"},
{"returnCode":"0","errorMessage":"success","Code":{},"phoneNumber":"400557705","mobile":"400089151"},
{"returnCode":"0","errorMessage":"success","Code":{},"phoneNumber":"400557706","mobile":"400089151"},
{"returnCode":"0","errorMessage":"success","Code":{},"phoneNumber":"400557707","mobile":"400089151"}];
var infoSingle = {"returnCode":"0","errorMessage":"success","Code":{},"phoneNumber":"400557704","mobile":"400089151"};
console.log(info.length); // prints 4; so you know it has the []
console.log(infoSingle.length); // prints undefined; so you know it doesn't have []

Do not try to re-invent the wheel.
There are many ways to parse JSON already:
Use JSON.parse.
Use jQuery.parseJSON