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Multi-push vs. multi-map [closed]

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I'm asked to get attributes collection out of an array object,
let a = [
{name:'aname',age:21},
{name:'bname',age:22},
{name:'cname',age:23},
{name:'dname',age:24},
{name:'ename',age:25},
{name:'fname',age:26},
{name:'gname',age:27}]
// wanted
let ok = {
names:'aname;bname;cname;dname;ename;fname;gname',
ages:'21;22;23;24;25;26;27'
}
and I got 2 ways of doing it:
alpha just using map of an array:
// alpha
let res = {
names:'',
ages:''
}
res.names=a.map(iter=>iter.name).join(';')
res.ages=a.map(iter=>iter.age).join(';')
//then return res
// ========================================================
and beta just iterate the array and append each attribute in the tabulation array:
// beta
let res = {
names:[],
ages:[]
}
a.forEach(iter=>{
res.names.push(iter.name)
res.ages.push(iter.age)
})
// then handle res's fields
ok.names = res.names.join(';')
ok.ages = res.ages.join(';')
so which way should I use to get the collection? Will alpha get slower or faster than beta when the objects in a get lots of fields(attrs)?

Both approaches are good. I'd say it depends on your personal preference what you'd want to use.
However, It seems to me that if you are aiming for performance, the following would yield better results.
let a = [
{name:'aname',age:21},
{name:'bname',age:22},
{name:'cname',age:23},
{name:'dname',age:24},
{name:'ename',age:25},
{name:'fname',age:26},
{name:'gname',age:27}]
let ok = { names: '', ages: ''}
for (let i = 0; i < a.length; i++){
const iter = a[i]
ok.names += iter.name + ";";
ok.ages += iter.age + ";";
}
ok.names = ok.names.slice(0,-1)
ok.ages = ok.ages.slice(0,-1)
console.log(ok)
This apporach eliminates the need to create new arrays or joining them (join is a heavy operation). Just create the string you want and at the end of it all, remove the one extra semicolon.

I consider that alfa is simpler and clearer for me, but I guess it is up to you...

Unexpected behaviour with for in a nodelist [closed]

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I have a nodelist with 30 divs and I need to include 1 div every 4 divs but the var 'c' does not change and stack all the divs in the position[6].
for (i = 0; i < 8; i++) {
var pub = "pub-retangulo-";
var c = 2;
c += 4;
var o = document.createElement("div");
o.setAttribute("id", pub.concat(i.toString()));
o.setAttribute("align", "center");
var container = document.querySelectorAll(".short-summary")[c];
container.parentNode.insertBefore(o, container);
}

You are redeclaring your c variable at each iteration. That is why is it stuck at 6. You need to move this assignation outside your loop
var pub = "pub-retangulo-";
var c = 2;
for (i = 0; i < 8; i++) {
var o = document.createElement("div");
o.setAttribute("id", pub.concat(i.toString()));
o.setAttribute("align", "center");
var container = document.querySelectorAll(".short-summary")[c];
container.parentNode.insertBefore(o, container);
c += 4;
}
I've also moved your c+=4 at the end of the loop, this will cause the loop to execute at c = 2 the first time rather than c = 6
As Barmar said, you might not need a variable at all in this case. You are incrementing by four each time, so you could replace your c variable with 2 (initial value) + i(current iteration index) * 4 (increment ratio).
P.S. This code is UNTESTED, please don't just copy and paste it expecting everything to work perfectly. Try to understand it and apply it to your own context.

I want to create a little test-program with "dices" with javascript [closed]

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I am trying to figure out how I can create a "game" where I have three dices, and three bets. If any of the bets hits, I will be granted 1 point, else nothing happens.
Example variables and arrays I would like to use;
var points = 1;
var slot1 = Math.floor((Math.random()*6)+1);
var slot2 = Math.floor((Math.random()*6)+1);
var slot3 = Math.floor((Math.random()*6)+1);
var dices = [slot1, slot2, slot3];
function Bet(bet1, bet2, bet3) {
"NEED HELP WITH THE CODE HERE"
}
Bet(1,2,3);
Thanks alot for all kinds of help!

I think a nudge in the right direction is more appropriate than a ready-to-go answer, since your question smells a little bit like homework :-)
You basically need to cross-check each item from both lists. You can do this with either a nested for .. in loop or a call to .some() with a nested .contains(). The latter will give you the cleanest solution. Docs
Alternatively, you can use Tagas' solution but that would make your function less reusable. If the number of bets vary, you'll need to adjust your function..

Try this:
function rollDice() {
//generate a number between 1 to 6
return Math.floor(Math.random() * (6 - 1 + 1)) + 1;
}
function makeBet(bet1, bet2, bet3) {
let slot1 = rollDice(),
slot2 = rollDice(),
slot3 = rollDice();
console.log('Slot 1:', slot1);
console.log('Slot 2:', slot2);
console.log('Slot 3:', slot3);
if(bet1 == slot1 || bet2 == slot2 || bet3 == slot3) {
//return 1 point as there is a match
return 1;
}
//return nothing as there was no match
return 0;
}
//Make a bet!
makeBet(1, 2, 3);

JS loop producing no result [closed]

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Trying to create an array with a loop and then sum all the contents of the array and put the result as the contents of a DIV but when I run the fiddle I get no result and jshint says everything is well formed.
var begin = 500000;
var stop = 999999;
var arrInt = [];
// Create an array worth summing
var CreateArray = function (begin,stop) {
while(begin < stop +1){
arrInt.push(begin++);
}
};
// Sum all ints in an array
var IntSum = function (ManyInts) {
var i = arr.length; while (i--) {
return;
}
};
var example = document.getElementById("example").innerHTML;
example=IntSum(arrInt);
<div id="example"></div>
http://jsfiddle.net/7b8rqme5/

At no point do you call CreateArray. You call your other function, IntSum, which does precisely nothing. Also, you create a variable example and assign a dom element to it, then you immediately overwrite it with a (noop) function result. There are additional issues with your code as well.
My advice: slow down, determine what it is you need to accomplish, and take it step by step.

I think this is what you wanted. But not really sure what you are trying to do here.
var begin = 500000;
var stop = 999999;
var arrInt = [];
var CreateArray = function (begin,stop) {
while(begin < stop +1){
arrInt.push(begin++);
}
};
var IntSum = function (ManyInts) {
var sum = 0
var i = ManyInts.length; while (i--) {
sum += ManyInts[i];
}
return sum;
};
var example = document.getElementById("example").innerHTML;
CreateArray(begin, stop);
var saic=IntSum(arrInt);
document.getElementById("example").innerHTML = saic
http://jsfiddle.net/wpnkL6k2/

How do I use repeated value in innerhtml? [closed]

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I used this code but it's not repeat
it increase the value but don't get to the initial value 0
please help
i=0;
function loading()
{
text=["Loading.","Loading..","Loading...","Loading...."];
window.setInterval(wr(),500)
}
function wr()
{
if(i<4)
{
wr='document.getElementById("text").innerHTML=text[i]';
alert(i);
}
else
i=0;
return wr;
}

Your code is way to complicated. Define a simple function which you pass to setInterval and make sure you increase the counter variable:
var i = 0; // initialize counter
var textElement = document.getElementById("text");
setInterval(function() {
i = i % 4; // make sure `i` is at max 3 and reset to 0
var text = 'Loading';
for (var j = i; j--; ) {
text += '.'; // add the correct number of periods
}
textElement.innerHTML = text; // set text
i++; // increase counter
}, 500);
DEMO

Here's a slight modification of a similar answer I gave a while back.
var i = 0;
setInterval(function() {
i = ++i % 4;
document.getElementById('text').innerHTML = "Loading"+Array(i+1).join(".");
}, 500);