What are the conditions that need to be met to use absolute positioning?

What are the conditions for using absolute positioning? Need specific code examples

Absolute positioning is a commonly used CSS positioning method, which allows an element to be positioned relative to its nearest non-static (i.e., an element whose position attribute value is other than static) positioned parent element (including body) ) for positioning. Before using absolute positioning, we need to understand some usage conditions and precautions.

1. Setting the positioning attribute of the parent element
   Before using absolute positioning, we need to ensure that the position attribute value of the parent element is not the default static, but relative, absolute or fixed. This is because absolute positioning is positioned relative to the nearest non-statically positioned parent element. If there is no qualified parent element, absolute positioning will be positioned relative to the entire document, which is usually not the desired result.

Sample code:
HTML:

<div class="parent">
  <div class="child">Hello World</div>
</div>

CSS:

.parent {
  position: relative;
}

.child {
  position: absolute;
  top: 50px;
  left: 50px;
}

2. Explicitly setting positioning properties
   In addition to requiring the parent element to set positioning Attribute, we also need to explicitly set the position attribute for the child element to be positioned, and set it to absolute or fixed. Only elements with the positioning attribute set can use absolute positioning.

Sample code:
HTML:

<div class="parent">
  <div class="child">Hello World</div>
</div>

CSS:

.parent {
  position: relative;
}

.child {
  position: absolute;
  top: 50px;
  left: 50px;
}

3. Specify positioning method
   Absolute positioning can be done through top, bottom, The left and right properties specify the distance from the edge of the parent element. We can use these properties to fine-tune the position of the element. Note that the value of the positioning attribute can be a specific pixel value or a percentage value.

Sample code:
HTML:

<div class="parent">
  <div class="child">Hello World</div>
</div>

CSS:

.parent {
  position: relative;
}

.child {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

4. Use the z-index attribute to control the cascading relationship
   Absolute positioning Elements may have overlapping cascading relationships. In this case, you can use the z-index attribute to control the display order of elements. Elements with larger z-index values ​​will overwrite elements with smaller z-index values. Please note that only elements with a position attribute value of relative, absolute, or fixed can set the z-index attribute.

Sample code:
HTML:

<div class="parent">
  <div class="child" style="z-index: 1;">Hello World</div>
  <div class="child" style="z-index: 2;">I am on top</div>
</div>

CSS:

.parent {
  position: relative;
}

.child {
  position: absolute;
  top: 50px;
  left: 50px;
}

Summary:
To use absolute positioning, we need to make sure the parent element is set Positioning attribute, the child element explicitly sets the position attribute, and specifies top, bottom, left, right and other positioning methods. The z-index attribute can be used to control the cascading relationship so that elements are displayed in the order we expect.

The above are some conditions and sample codes about using absolute positioning. I hope it will be helpful to you.

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