Develop Reference

How to ignore the loop in else case

I have to compare two values. Both values came from different loops.
if the value is an exact match, I push the array differently.
As you can see in the code. I cant use an "else" after the "if" function because it will literate till the loop stop. I would have multiple pushes.
If I add the array.push after the loop there will be 2 pushes.
for (var prop in obj) {
var array = []
for (var item in obj[prop]) {
for (var i = 0; i < doctyp88.length; i += 1) {
var doctyp88ID = doctyp88[i]._id;
var doctyp88name = doctyp88[i]._source['88_name'];
if (item == doctyp88ID) {
array.push({
"name": item,
"count": obj[prop][item],
"archivname": doctyp88name,
});
}
}
array.push({
"name": item,
"count": obj[prop][item],
});
}
}
What is the best way to avoid my problem?

for (var prop in obj) {
var array = []
for (var item in obj[prop]) {
const newObj = {
"name": item,
}
for (var i = 0; i < doctyp88.length; i += 1) {
var doctyp88ID = doctyp88[i]._id;
var doctyp88name = doctyp88[i]._source['88_name'];
newObj.count= obj[prop][item],
if (item == doctyp88ID) {
newObj.archivname = doctyp88name
}
}
array.push(newObj);
}
}

If I understood your question correctly you could use break [label]; statement to exit from nested loop and skip more pushes but don't exit outside for like this:
loop_1:
for (var prop in obj) {
var array = []
loop_2:
for (var item in obj[prop]) {
loop_3:
for (var i = 0; i < doctyp88.length; i += 1) {
var doctyp88ID = doctyp88[i]._id;
var doctyp88name = doctyp88[i]._source['88_name'];
if (item == doctyp88ID) {
array.push({
"name": item,
"count": obj[prop][item],
"archivname": doctyp88name,
});
break loop_2;
}
}
array.push({
"name": item,
"count": obj[prop][item],
});
}
}

How to concatenate values of duplicate keys

When reading a csv into a javascript dictionary, how can I concatenate values of what would otherwise be duplicate keys? I've seen answers for how to do this with bash, c#, and perl, but I haven't been able to find answers for Javascript. Here's what I have:
var subjects = {};
d3.csv("test.csv", function(data) {
for (var i = 0; i < data.length; i++)
{
subjects[data[i].Id] = data[i].VALUE;
}
console.log(subjects);
});
This, obviously writes over existing keys. Instead, I want the key to be an array of the values. The csv basically looks like:
Id, VALUE
id1, subject1
id2, subject1
id1, subject3
And I want to output as:
{"id1": ["subject1", "subject3"], "id2": ["subject1"]...}

Just check if your output already has the key, if so you add the new value to the array. Else you create an array.
d3.csv("test.csv", function(data) {
var subjects = {};
for (var i = 0; i < data.length; i++)
{
// Check if key already exists
if(subjects.hasOwnProperty(data[i].Id)){
// push data to array
subjects[data[i].Id].push(data[i].VALUE);
}else{
// create new key and array
subjects[data[i].Id] = [data[i].VALUE];
}
}
console.log(subjects);
});

You could make it into an array and then push the content into that array
var subjects = {};
d3.csv("test.csv", function(data) {
for (var i = 0; i < data.length; i++)
{
//first time we see this id, turn it into an array
if(typeof subjects[data[i].Id] != "object"){
subjects[data[i].Id] = [];
}
//push content to the array
subjects[data[i].Id].push(data[i].VALUE);
}
console.log(subjects);
});

Try this inside the for loop:
typeof subjects[data[i].Id] == 'undefined' && (subjects[data[i].Id] = []);
subjects[data[i].Id].push(data[i].VALUE);

You can reduce the footprint of your code slightly if you use reduce:
var out = data.reduce((p, c) => {
const id = c.Id;
p[id] = p[id] || [];
p[id].push(c.VALUE);
return p;
}, {});
RESULT
{
"id1": [
"subject1",
"subject3"
],
"id2": [
"subject1"
]
}
DEMO

How to iterate over an array in an array

I want to iterate over my 'areasarray' in the array 'areas' dataprovider array,
I have no idea how to loop over an array in an array, I've tried several tries with for-loops but none of it succeeded.
this is amCharts Maps framework.
var areasarray = {};
//get JSON File
$(function getData() {
var url = "../assets/document.json";
$.ajax({
url: url,
dataType: 'json',
success: function (data) {
console.log(data);
for (var i = 0; i < data.fact.length; i++) {
if (inverseCountryCodes[data.fact[i].dims.COUNTRY] != null) {
areasarray[i] = {
"id": inverseCountryCodes[data.fact[i].dims.COUNTRY],
"value": data.fact[i].Value,
"info": "Verkeersdoden per 100 000 inwoners: " + data.fact[i].Value
}
}
}
//console.log(areasarray);
//Map initialiseren
var map;
map = new AmCharts.AmMap();
map.colorSteps = 20;
var dataProvider =
{
mapVar: AmCharts.maps.worldLow
areas: [
{
id: "BE",
value: 10,
info: "Verkeersdoden ..."
}
]
};
console.log(dataProvider);
map.areasSettings = {
autoZoom: true,
selectedColor: "#338DAB"
};
map.dataProvider = dataProvider;
var valueLegend = new AmCharts.ValueLegend();
valueLegend.right = 10;
valueLegend.minValue = "little";
valueLegend.maxValue = "a lot!";
map.valueLegend = valueLegend;
map.addListener("clickMapObject", function (event) {
document.getElementById("info").innerHTML = '<p><b>' + event.mapObject.title + '</b></p><p>' + event.mapObject.info + '</p>';
});
map.mouseWheelZoomEnabled = true;
map.write("mapdiv");
}
});
});

If you want to iterate over areasarray which is actually an object and not an array you should look into using a for...in loop
For iterating over arrays within arrays, one approach would be to nest for loops
for(var i = 0; i < array1.length; i++) {
for(var j = 0; j < array2.length; j++) {
// do something
}
}
It's not clear to me what you mean by "array in an array" in this context and it would help if you provided more information about what exactly you are trying to accomplish

I would try a nested loop. Here is an example of creating an array of arrays and then looping through each.
var matrix = []
matrix[1] = []
matrix[1][1] = "foo"
matrix.forEach(function(column){
column.forEach(function(cell){
console.log(cell);
});
});

var areasarray = {}; means it's an object, not an array.
To iterate through each items in this object, try this.
var keys = Object.keys(areasarray);
keys.forEach(function(k) {
// you can access your item using
// k is the property key
console.log(areasarray[k]);
console.log(areasarray[k].id);
console.log(areasarray[k].value);
console.log(areasarray[k].info);
});
Not sure why you chose to create areasarray as an object.
If you wanted to, you could have defined it as:
var areasarray = [];
Then when adding to the array you use:
areasarray.push({
"id": inverseCountryCodes[data.fact[i].dims.COUNTRY],
"value": data.fact[i].Value,
"info": "Verkeersdoden per 100 000 inwoners: " + data.fact[i].Value
});
So later on, you can simply do:
for (var i = 0; i < areasarray.length; i++) {
console.log(areasarray[i]);
console.log(areasarray[i].id);
console.log(areasarray[i].value);
console.log(areasarray[i].info);
}
Note: in the above code, i is an index, where in the object block code, k is a key to the object.

Use nested loops.
Example:
var a1=["1","2","3","4","5","6","7"];
var a2=["a","b","c","d","e"];
for(var i=0;i<a1.length;i++) //loop1
{
console.log(a1[i]);
for(var j=0;j<a2.length;j++) //loop2
{
console.log(a2[j]);
}
}
Sample Output:
1st iteration of loop1:
1abcde
2nd iteration of loop1:
2abcde
and so on...
For every iteration of loop1,loop2 iterates 4 times(j<5).
Hoping I got your question right...This could be an answer.!

loop a JS Object

I have this JS object:
{
"data": {
"nid": [{
"cid": "32",
"uid": "780",
"comment": "text"
}]
},
"request_status": "found"
}
how can I loop through these items to get comment value ("comment":"text")?

You don't really need to loop to get it. Just do...
var obj = {"data":{"nid":[{"cid":"32","uid":"780","comment":"text"}]},"request_status":"found"};
var text = obj.data.nid[0].comment;
Or if there are several, you can use forEach...
obj.data.nid.forEach(function(val,i) {
alert( val.comment );
});
Or a traditional for loop...
for( var i = 0; i < obj.data.nid.length; i++ ) {
alert( obj.data.nid[i].comment );
}
Or if you want to build an Array, use map...
var arr = obj.data.nid.map(function(val,i) {
return val.comment;
});
Or again a traditional for loop...
var arr = []
for( var i = 0; i < obj.data.nid.length; i++ ) {
arr.push( obj.data.nid[i].comment );
}

Given:
var obj = {
"data": {
"nid": [{
"cid": "32",
"uid": "780",
"comment": "text"
}]
},
"request_status": "found"
};
The direct way to retrieve the comment is:
obj["data"]["nid"][0]["comment"]
// or
obj.data.nid[0].comment
As far as "looping" through the items to get the value, I'm not sure how a loop makes sense. Are you saying you might not know the structure of the object but you know it will have a "comment" field in there somewhere?
The "nid" array only has one item in it - if this was just a sample but really you'll have an array with more values you can loop through that array:
var nid = obj["data"]["nid"], // get a direct reference to the array to save
i; // repeating obj.data.nid everywhere
for (i=0; i < nid.length; i++) {
// do something with the comment in the current item
console.log(nid[i]["comment"]);
}

If you're just referring to that specific object (or if every object you are working with follows that same pattern), then you can just access the value directly:
var theObj = {"data":{"nid":[{"cid":"32","uid":"780","comment":"text"}]},"request_status":"found"};
alert(theObj.data.nid[0].comment);
If you want to do something iterative, then perhaps try this:
var theObj = {"data":{"nid":[{"cid":"32","uid":"780","comment":"text"}]},"request_status":"found"};
for (var index = 0; index < theObj.data.nid.length; index++) {
var item = theObj.data.nid[index];
if (item.comment) {
alert(item.comment);
}
}
Or if you really want to do the entire thing iteratively:
window.searchObj = function(theObj) {
if (theObj.comment) {
alert(theObj.comment);
}
if (theObj instanceof Array) {
searchArray (theObj);
}
else if (theObj instanceof Object) {
for (var key in theObj) {
searchObj(theObj[key]);
}
}
};
window.searchArray = function(theArray) {
for (var index = 0; index < theArray.length; index++) {
var item = theArray[index];
searchObj(item);
}
};
var theObj = {"data":{"nid":[{"cid":"32","uid":"780","comment":"text"}]},"request_status":"found"};
searchObj(theObj);

Is there a more efficent way of selecting a particular object inside an array of objects

Given the following data structure
var things = [{ "name": "thing1", "sex": "male"},
{ "name": "thing2", "sex": "female"}];
I would like to be able to search that array of objects and pull out a particular object.
I currently have the following code written
function selectElementByName (name) {
var returnObject;
for (var i = 0; i < things.length; i++) {
if (things[i].name === name) {
returnObject = things[i];
}
}
if ( returnObject === undefined) {
console.log("Object not found");
}
return returnObject;
}
JsFiddle can be found here
Is there a more efficient way of doing this?

You can make an early exit when an object is found, so that you don't have to loop through the rest of the array:
function selectElementByName(name) {
for (var i = 0; i < things.length; i++) {
if (things[i].name === name) {
return things[i];
}
}
console.log("Object not found");
}
(This will however change the behaviour if there are duplicates, so that it returns the first object found instead of the last.)
If the names are unique, you could use them as key and store the objects in an object instead of in an array:
var things = {
"thing1": { "name": "thing1", "sex": "male"},
"thing2": { "name": "thing2", "sex": "female"}
};
Then you wouldn't need to loop to find an object:
function selectElementByName(name) {
return things[name];
}
If you need the objects in an array, you could still create an index for searching if the array doesn't change so often:
var thingsNameIndex = {};
for (var i = 0; i < things.length; i++) {
thingsNameIndex[things[i].name] = i;
}
Now you can use the index to find the object:
function selectElementByName(name) {
return things[thingsNameIndex[name]];
}
As you have to update or recreate the index as soon as the array changes, this would only be usedful if you do searches in the array much more often than you change the array.

In more recent versions of JavaScript:
var selectElementByName = function(name) {
// This will fetch all items that match the filter
// and place them in a new array
var items = things.filter(function(item) {
return item.name === name;
});
// If there isn't anything in the array, log the error and return.
if (!items.length) {
console.log("Object not found");
return;
}
// Return the first matched element in the array.
return items[0];
};

You can break once it's found at least:
for (var i = 0; i < things.length; i++) {
if (things[i].name === name) {
returnObject = things[i];
break;
}
}