How to make iframe to fit 100 of containers remaining height

When developing web applications, it is often necessary to make an iframe adapt to the remaining height of its container. This is typically done to ensure that the content within the iframe is displayed properly without additional scrollbars or unused space. There are several methods to solve this issue:

Method One: CSS Flexbox

Using CSS Flexbox layout can conveniently achieve adaptive height for the iframe. Assume you have a parent container containing other elements and an iframe; you can set the parent container to a flex layout and let the iframe occupy all available space.

HTML Structure Example:

html
<div class="container">
  <div class="header">
    <!-- Other content -->
  </div>
  <iframe class="flexible-iframe" src="example.html"></iframe>
</div>

CSS Styles:

css
.container {
  display: flex;
  flex-direction: column;
  height: 100vh; /* Assuming you want the overall container to fill the viewport height */
}

.header {
  /* Height adapts based on content */
}

.flexible-iframe {
  flex: 1; /* Occupies all available space */
}

Method Two: JavaScript Dynamic Adjustment

If for some reason CSS methods are not applicable to your situation, you can use JavaScript to dynamically adjust the iframe's height. This method dynamically adjusts the height when the iframe content changes.

Example Code:

javascript
window.addEventListener("load", function() {
  var iframe = document.querySelector("iframe");
  var containerHeight = document.querySelector(".container").clientHeight;
  var otherContentHeight = document.querySelector(".header").clientHeight;
  
  iframe.style.height = containerHeight - otherContentHeight + "px";
});

Method Three: Using CSS vh Units

If the iframe is positioned lower on the page and the elements above have fixed heights, you can directly use the viewport height (vh) unit to set the iframe's height.

Example Code:

css
.header {
  height: 50px; /* Assuming header height is 50px */
}

.flexible-iframe {
  height: calc(100vh - 50px); /* Remaining viewport height */
}

Real-World Application Example

In a real-world project, we needed to embed an iframe of a reporting system within the dashboard of a management system. We used the Flexbox method because it provides the most flexible layout solution and can automatically adapt to other dynamic parts of the interface, such as collapsible sidebars. By setting flex: 1, the iframe always occupies all available space except for the top navigation bar and sidebar, regardless of viewport size changes.

These are several methods to make an iframe adapt to the remaining height of its container. Depending on project requirements and layout characteristics, choose the most suitable method to implement.

To set the iframe to fill 100% of the remaining height of its container, we can take the following steps:

1. Ensure the parent container has the correct height: First, ensure the parent container has a defined height. If the parent container lacks a set height, the iframe cannot determine its height using percentages. For example, we can set a fixed height for the parent container or use a percentage of the screen height.

2. CSS Styles: We can use CSS to ensure the iframe adapts to the remaining height of its parent container. Here is a CSS example where .container is the class name for the parent container, and .responsive-iframe is the class name for the iframe.

css
.container {
  position: relative; /* or flex layout can also be used */
  height: 500px; /* for example, fixed height or using vh units */
}

.responsive-iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
}

1. HTML Structure: Ensure the iframe is placed inside the parent container with a defined height and applies the corresponding CSS class.

html
<div class="container">
    <iframe src="your-frame-source.html" frameborder="0" class="responsive-iframe"></iframe>
</div>

1. Consider other elements within the container: If the container contains additional elements, calculate their occupied space so the iframe can fill the remaining area. This may require dynamically computing the heights of other elements and adjusting the iframe's height accordingly.

2. Use JavaScript for dynamic adjustment: To dynamically adjust the iframe size for different screen sizes or content changes, use JavaScript to listen for window resize events and calculate/set the iframe's height dynamically.

javascript
window.addEventListener('resize', function() {
  var containerHeight = document.querySelector('.container').clientHeight;
  var iframe = document.querySelector('.responsive-iframe');
  iframe.style.height = containerHeight + 'px';
});

This is how to set the iframe to fill the remaining height of its parent container.