CODEWITHSUNDEEP
javascriptjquery
nehel
nehel

Reputation: 885

Concatenate string through for loop

I'm trying to concatenate strings via for loop but i'm receiving NaNs. What i want to achieve is to get one concatenated string Div #0, Div #1, Div #2, Div #3,.

var divLength = $('div').length;

var str = '';
for(var i=0; i<divLength; i++){
  var str =+ "Div #" + [i] + ", ";
  console.log(str);
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div></div>
<div></div>
<div></div>
<div></div>

Upvotes: 17

Views: 115278

Answers (6)

Mykhailo Zakharkiv
Mykhailo Zakharkiv

Reputation: 1

var divLength = $('div').length;

var str = '';
for (var i=0; i<divLength; i++) {
  var str += `Div # ${i} , `;
  console.log(str);
}

Should work jus fine. You have to add ${i} to the string inside or it will give u NaN

Upvotes: 0

Denise Ignatova
Denise Ignatova

Reputation: 533

let str = ''
for (let i = 0; i < arr; i++) {
   str += `${arr[i]}`
}

This worked in my case.

Upvotes: 0

Alejandromusic
Alejandromusic

Reputation: 123

From Typescript ESLint recommendations,

For cases where the index is only used to read from the array being iterated, a for-of loop is easier to read and write.

We can use for-of using the keys method.

let str = ''
for (const i of Array(divLength).keys()) {
  str += `Div #${i}, `;
}
console.log(str);

But that has the problem of the trailing comma. We can let JavaScript take care of that using the join method.

const arr = Array.from(Array(divLength).keys()); // [ 0, 1, 2];
const divArray = arr.map(n => `Div #${n}`)       // ['Div #0', 'Div #1', 'Div #2']
const str = divArray.join(', ');                 // 'Div #0, Div #1, Div #2'

which can be wrapped up as a one-liner,

const s = Array.from(Array(divLength).keys()).map(val => `Div #${val}`).join(', ')

A somewhat less verbose one-liner can be done using fill method

const s = Array(divLength).fill().map((_, i) => `Div #${i}`).join(', ')

Upvotes: 3

Red Mercury
Red Mercury

Reputation: 4310

Don't declare a new str variable inside the loop with var str. Reuse the one you declare outside the loop. Also do += 

var divLength = $('div').length;

var str = '';
for(var i = 0; i < divLength; i++) {
  str += "Div #" + i + ", ";
  console.log(str);
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div></div>
<div></div>
<div></div>
<div></div>

Upvotes: 33

Sagar Paithankar
Sagar Paithankar

Reputation: 1

If we are concatenating the string for an array then you can do like this. For loop is also best solution but it becomes vast process:

if(this.questionData.length > 0) {
    this.questionData.forEach(questions => {this.questionsParams += '&question'+ questions.question +'=' + questions.value;
    });
}

Perfect solution output like this : &question1=1&question2=0&question3=1&question4=0

Upvotes: 0

Sebastian D&#39;Agostino
Sebastian D&#39;Agostino

Reputation: 1675

Besides the selected answer, you could do this with a forEach if you have a list of stuff to put inside those divs:

let string = '';
items.forEach(item => string += '<div>'+ item.description + '</div>');

Upvotes: 11

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