3

I have this simple read more JS function. I want to reuse it, what's the best practice for this? For example, below, I have two read more buttons but I have to copy paste the function and some number to it to use it. Not the cleanest way, what's a better way around this?

function myFunction() {
  var dots = document.getElementById("dots");
  var moreText = document.getElementById("more");
  var btnText = document.getElementById("myBtn");

  if (dots.style.display === "none") {
    dots.style.display = "inline";
    btnText.innerHTML = "Read more";
    moreText.style.display = "none";
  } else {
    dots.style.display = "none";
    btnText.innerHTML = "Read less";
    moreText.style.display = "inline";
  }
}

function myFunction2() {
  var dots = document.getElementById("dots2");
  var moreText = document.getElementById("more2");
  var btnText = document.getElementById("myBtn2");

  if (dots.style.display === "none") {
    dots.style.display = "inline";
    btnText.innerHTML = "Read more";
    moreText.style.display = "none";
  } else {
    dots.style.display = "none";
    btnText.innerHTML = "Read less";
    moreText.style.display = "inline";
  }
}
#more {display: none;}
#more2 {display: none;}
<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Phasellus imperdiet, nulla et dictum interdum, nisi lorem egestas vitae scel<span id="dots">...</span><span id="more">erisque enim ligula venenatis dolor. Maecenas nisl est, ultrices nec congue eget, auctor vitae massa. Fusce luctus vestibulum augue ut aliquet. Nunc sagittis dictum nisi, sed ullamcorper ipsum dignissim ac. In at libero sed nunc venenatis imperdiet sed ornare turpis. Donec vitae dui eget tellus gravida venenatis. Integer fringilla congue eros non fermentum. Sed dapibus pulvinar nibh tempor porta.</span></p>

<button onclick="myFunction()" id="myBtn">Read more</button>


<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Phasellus imperdiet, nulla et dictum interdum, naliquet. Nunc sagittis dictum nisi, sed ullamcorper ipsum dignissim ac. In at libero sed nunc venenatis imperdiet sed ornare turpis. Donec vitae dui eget tellus gravida aliquet. Nunc sagittis dictum nisi, sed ullamcorper ipsum dignissim ac. In at libero sed nunc venenatis imperdiet sed ornare turpis. Donec vitae dui eget tellus gravida isi lorem egestas vitae scel<span id="dots2">...</span><span id="more2">erisque enim ligula venenatis dolor. Maecenas nisl est, ultrices nec congue eget, auctor vitae massa. Fusce luctus vestibulum augue ut aliquet. Nunc sagittis dictum nisi, sed ullamcorper ipsum dignissim ac. In at libero sed nunc venenatis imperdiet sed ornare turpis. Donec vitae dui eget tellus gravida venenatis. Integer fringilla congue eros non fermentum. Sed dapibus pulvinar nibh tempor porta.</span></p>

<button onclick="myFunction2()" id="myBtn2">Read more</button>

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2
  • pass in the ids of the button Commented Dec 29, 2021 at 13:52
  • if you did <p class="read-more"> you could look fo them items by class, loop over them then add the buttons dynamically which you can add the event to without needing ids, js can do more than toggle styling Commented Dec 29, 2021 at 14:06

4 Answers 4

Reset to default
5

First, when repeating behavior you should refrain from attempting to use id attributes since (as you know) they must be unique. Additionally, it leads to naming things without much meaning (thing1, thing2 etc).

One technique is to use the class attribute.

Each event allows access to the target of the event. We can find the paragraph to effect using the previousElementSibling to find the <p>.

From there, we can use that node to query for the .dots and .more classes and change them as needed.

Since the button is the target of the event, we just change the button text directly.

EDIT: Thanks @Carston for the previousElementSibling hint.

function myFunction(e) {
  const paragraph = e.target.previousElementSibling;
  var dots = paragraph.querySelector('.dots');
  var moreText = paragraph.querySelector(".more");

  if (dots.style.display === "none") {
    dots.style.display = "inline";
    e.target.innerHTML = "Read more";
    moreText.style.display = "none";
  } else {
    dots.style.display = "none";
    e.target.innerHTML = "Read less";
    moreText.style.display = "inline";
  }
}
.more {display: none;}
<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Phasellus imperdiet, nulla et dictum interdum, nisi lorem egestas vitae scel<span class="dots">...</span><span class="more">erisque enim ligula venenatis dolor. Maecenas nisl est, ultrices nec congue eget, auctor vitae massa. Fusce luctus vestibulum augue ut aliquet. Nunc sagittis dictum nisi, sed ullamcorper ipsum dignissim ac. In at libero sed nunc venenatis imperdiet sed ornare turpis. Donec vitae dui eget tellus gravida venenatis. Integer fringilla congue eros non fermentum. Sed dapibus pulvinar nibh tempor porta.</span></p>

<button onclick="myFunction(event)">Read more</button>


<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Phasellus imperdiet, nulla et dictum interdum, naliquet. Nunc sagittis dictum nisi, sed ullamcorper ipsum dignissim ac. In at libero sed nunc venenatis imperdiet sed ornare turpis. Donec vitae dui eget tellus gravida aliquet. Nunc sagittis dictum nisi, sed ullamcorper ipsum dignissim ac. In at libero sed nunc venenatis imperdiet sed ornare turpis. Donec vitae dui eget tellus gravida isi lorem egestas vitae scel<span class="dots">...</span><span class="more">erisque enim ligula venenatis dolor. Maecenas nisl est, ultrices nec congue eget, auctor vitae massa. Fusce luctus vestibulum augue ut aliquet. Nunc sagittis dictum nisi, sed ullamcorper ipsum dignissim ac. In at libero sed nunc venenatis imperdiet sed ornare turpis. Donec vitae dui eget tellus gravida venenatis. Integer fringilla congue eros non fermentum. Sed dapibus pulvinar nibh tempor porta.</span></p>

<button onclick="myFunction(event)">Read more</button>

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4 Comments

I just would have just posted pretty same solution, but no keyboard on my phone :) I think this makes a much more repeatable (so reusable) and nicely capsulated solution.
Yes +1 from me too. Further hint: you can use previousElementSibling once instead of your previousSibling.previousSibling construct.
@CarstenMassmann - Thanks edited with your improvement.
@CarstenMassmann - oh - I thought I did! I must not have saved the edit. Will fix.
4

You could use a function parameter to dynamically add a suffix to your ids :

function myFunction(suffix) {
  var dots = document.getElementById("dots" + suffix);
  var moreText = document.getElementById("more"  + suffix);
  var btnText = document.getElementById("myBtn"  + suffix);

  if (dots.style.display === "none") {
    dots.style.display = "inline";
    btnText.innerHTML = "Read more";
    moreText.style.display = "none";
  } else {
    dots.style.display = "none";
    btnText.innerHTML = "Read less";
    moreText.style.display = "inline";
  }
}
#more {display: none;}
#more2 {display: none;}
<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Phasellus imperdiet, nulla et dictum interdum, nisi lorem egestas vitae scel<span id="dots">...</span><span id="more">erisque enim ligula venenatis dolor. Maecenas nisl est, ultrices nec congue eget, auctor vitae massa. Fusce luctus vestibulum augue ut aliquet. Nunc sagittis dictum nisi, sed ullamcorper ipsum dignissim ac. In at libero sed nunc venenatis imperdiet sed ornare turpis. Donec vitae dui eget tellus gravida venenatis. Integer fringilla congue eros non fermentum. Sed dapibus pulvinar nibh tempor porta.</span></p>

<button onclick="myFunction('')" id="myBtn">Read more</button>


<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Phasellus imperdiet, nulla et dictum interdum, naliquet. Nunc sagittis dictum nisi, sed ullamcorper ipsum dignissim ac. In at libero sed nunc venenatis imperdiet sed ornare turpis. Donec vitae dui eget tellus gravida aliquet. Nunc sagittis dictum nisi, sed ullamcorper ipsum dignissim ac. In at libero sed nunc venenatis imperdiet sed ornare turpis. Donec vitae dui eget tellus gravida isi lorem egestas vitae scel<span id="dots2">...</span><span id="more2">erisque enim ligula venenatis dolor. Maecenas nisl est, ultrices nec congue eget, auctor vitae massa. Fusce luctus vestibulum augue ut aliquet. Nunc sagittis dictum nisi, sed ullamcorper ipsum dignissim ac. In at libero sed nunc venenatis imperdiet sed ornare turpis. Donec vitae dui eget tellus gravida venenatis. Integer fringilla congue eros non fermentum. Sed dapibus pulvinar nibh tempor porta.</span></p>

<button onclick="myFunction('2')" id="myBtn2">Read more</button>

Or 3 parameters corresponding to the ids :

function myFunction(dotsId, moreTextId, btnTextId) {
  var dots = document.getElementById(dotsId);
  var moreText = document.getElementById(moreTextId);
  var btnText = document.getElementById(btnTextId);

  if (dots.style.display === "none") {
    dots.style.display = "inline";
    btnText.innerHTML = "Read more";
    moreText.style.display = "none";
  } else {
    dots.style.display = "none";
    btnText.innerHTML = "Read less";
    moreText.style.display = "inline";
  }
}
#more {display: none;}
#more2 {display: none;}
<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Phasellus imperdiet, nulla et dictum interdum, nisi lorem egestas vitae scel<span id="dots">...</span><span id="more">erisque enim ligula venenatis dolor. Maecenas nisl est, ultrices nec congue eget, auctor vitae massa. Fusce luctus vestibulum augue ut aliquet. Nunc sagittis dictum nisi, sed ullamcorper ipsum dignissim ac. In at libero sed nunc venenatis imperdiet sed ornare turpis. Donec vitae dui eget tellus gravida venenatis. Integer fringilla congue eros non fermentum. Sed dapibus pulvinar nibh tempor porta.</span></p>

<button onclick="myFunction('dots','more','myBtn')" id="myBtn">Read more</button>


<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Phasellus imperdiet, nulla et dictum interdum, naliquet. Nunc sagittis dictum nisi, sed ullamcorper ipsum dignissim ac. In at libero sed nunc venenatis imperdiet sed ornare turpis. Donec vitae dui eget tellus gravida aliquet. Nunc sagittis dictum nisi, sed ullamcorper ipsum dignissim ac. In at libero sed nunc venenatis imperdiet sed ornare turpis. Donec vitae dui eget tellus gravida isi lorem egestas vitae scel<span id="dots2">...</span><span id="more2">erisque enim ligula venenatis dolor. Maecenas nisl est, ultrices nec congue eget, auctor vitae massa. Fusce luctus vestibulum augue ut aliquet. Nunc sagittis dictum nisi, sed ullamcorper ipsum dignissim ac. In at libero sed nunc venenatis imperdiet sed ornare turpis. Donec vitae dui eget tellus gravida venenatis. Integer fringilla congue eros non fermentum. Sed dapibus pulvinar nibh tempor porta.</span></p>

<button onclick="myFunction('dots2','more2','myBtn2')" id="myBtn2">Read more</button>

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Comments

1

use template literals like this:

function myFunction(number) {
  var dots = document.getElementById(`dots${number}`);
  var moreText = document.getElementById(`more${number}`);
  var btnText = document.getElementById(`myBtn${number}`);

  if (dots.style.display === "none") {
    dots.style.display = "inline";
    btnText.innerHTML = "Read more";
    moreText.style.display = "none";
  } else {
    dots.style.display = "none";
    btnText.innerHTML = "Read less";
    moreText.style.display = "inline";
  }
}

<button onclick="myFunction('')" id="myBtn">Read more</button>
<button onclick="myFunction2('2')" id="myBtn2">Read more</button>
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0

I guess this answer was not really called for. In my opinion @RandyCasburn already nailed it. However, here is another version that works with even less html to put in place to create unfoldable sections.

By placing a <span class="more"></span> within a paragraph this section is marked to be "unfoldable". The first part of my script adds the three dots and a "Read more" button and makes the span's original content invisible.

The delegated click event handler then does all the work: 

// prepare document once (put "..." and buttons in place): 
document.querySelectorAll(".more").forEach(el=>{
  el.dataset.html=el.innerHTML;
  el.textContent="...";
  const btn=document.createElement("button");
  btn.className="morebtn";
  btn.textContent="Read more";
  el.closest("p").after(btn);
}) 

// delegated event attachment:
document.body.onclick=e=>{
 if (e.target.className==="morebtn"){
  const mor = e.target.previousElementSibling.querySelector(".more");
  [mor.innerHTML,mor.dataset.html]=[mor.dataset.html,mor.innerHTML];
  e.target.innerHTML = mor.textContent==="..."?"Read more":"Read less";
 }
}
<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Phasellus imperdiet, nulla et dictum interdum, nisi lorem egestas vitae scel<span class="more">erisque enim ligula venenatis dolor. Maecenas nisl est, ultrices nec congue eget, auctor vitae massa. Fusce luctus vestibulum augue ut aliquet. Nunc sagittis dictum nisi, sed ullamcorper ipsum dignissim ac. In at libero sed nunc venenatis imperdiet sed ornare turpis. Donec vitae dui eget tellus gravida venenatis. Integer fringilla congue eros non fermentum. Sed dapibus pulvinar nibh tempor porta.</span></p>
<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Phasellus imperdiet, nulla et dictum interdum, naliquet. Nunc sagittis dictum nisi, sed ullamcorper ipsum dignissim ac. In at libero sed nunc venenatis imperdiet sed ornare turpis. Donec vitae dui eget tellus gravida aliquet. Nunc sagittis dictum nisi, sed ullamcorper ipsum dignissim ac. In at libero sed nunc venenatis imperdiet sed ornare turpis. Donec vitae dui eget tellus gravida isi lorem egestas vitae scel<span class="more">erisque enim ligula venenatis dolor. Maecenas nisl est, ultrices nec congue eget, auctor vitae massa. Fusce luctus vestibulum augue ut aliquet. Nunc sagittis dictum nisi, sed ullamcorper ipsum dignissim ac. In at libero sed nunc venenatis imperdiet sed ornare turpis. Donec vitae dui eget tellus gravida venenatis. Integer fringilla congue eros non fermentum. Sed dapibus pulvinar nibh tempor porta.</span></p>
<p>And another paragraph with more nonsensical text that will only <span class="more">be shown completely, once the "Read more" button was hit.</span></div>

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