object-fit property specifies how the contents of a replaced element should be fitted to the box established by its used height and width.
If the content does not completely fill the replaced element's content box, the unfilled space shows the replaced element's background. Since replaced elements always clip their contents to the content box, the content will never overflow.
What is a Replaced Element?
According to the CSS specification, a replaced element is an element whose content is outside the scope of the CSS formatting model, such as an image, embedded document, or applet.
According to the HTML specification the following elements are replaced elements:
<value> is one of the values below.
Here are the possible values for this property:
- Specifies that the replaced content is sized to fill the element's content box.
- Specifies that the replaced content is sized to maintain its aspect ratio while fitting within the element's content box.
- Specifies that the replaced content is sized to maintain its aspect ratio while filling the element's entire content box.
- Specifies that the replaced content is not resized to fit inside the element's content box. The content's intrinsic aspect ratio is maintained.
- Specifies that the content is sized as if
containwere specified, whichever would result in a smaller concrete object size.
In addition, all CSS properties also accept the following CSS-wide keyword values as the sole component of their property value:
- Represents the value specified as the property's initial value.
- Represents the computed value of the property on the element's parent.
- This value acts as either
initial, depending on whether the property is inherited or not. In other words, it sets all properties to their parent value if they are inheritable or to their initial value if not inheritable.
Here are examples to show the effect of each of these values.
Basic Property Information
- Initial Value
- Applies To
- Replaced elements
- Discrete (see example)
object-fit property is defined in CSS Images Module Level 3 (W3C Candidate Recommendation, 10 October 2019)
The following table provided by Caniuse.com shows the level of browser support for this feature.
For maximum browser compatibility many web developers add browser-specific properties by using extensions such as
-webkit- for Safari, Google Chrome, and Opera (newer versions),
-ms- for Internet Explorer,
-moz- for Firefox,
-o- for older versions of Opera etc. As with any CSS property, if a browser doesn't support a proprietary extension, it will simply ignore it.
This practice is not recommended by the W3C, however in many cases, the only way you can test a property is to include the CSS extension that is compatible with your browser.
The major browser manufacturers generally strive to adhere to the W3C specifications, and when they support a non-prefixed property, they typically remove the prefixed version. Also, W3C advises vendors to remove their prefixes for properties that reach Candidate Recommendation status.
Many developers use Autoprefixer, which is a postprocessor for CSS. Autoprefixer automatically adds vendor prefixes to your CSS so that you don't need to. It also removes old, unnecessary prefixes from your CSS.
You can also use Autoprefixer with preprocessors such as Less and Sass.