CSS選擇器

Web開發
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CSS選擇器

CSS 選擇器是 CSS 規則的㇐部分。能選定要調整哪個（或哪些）元素的樣式(Style)。

  • h1{ color: blue; }：指向文件中特定標籤的所有元素
  • #id { color: blue; }：指向文件中擁有特定id的單㇐元素
  • .class { color: blue; }：指向文件中擁有特定class的所有元素
  • div > p { color: blue; }：指向文件中以div為父元素的標籤為<p>的子元素
  • * 指向文件中所有的元素
    範例：
* {margin: 0; //設定所有元素的margin為0
   Padding: 0; //設定所有元素的padding為0
   }
  • [attribute=value]：指向文件中特定標籤屬性「等同」特定值的元素
  • [attribute~=value]：指向文件中特定標籤屬性「包含」特定值的元素
  • .class1.class2：指向文件中為class同時為「class1」與「class2」的 元素
  • .class1 .class2：指向文件中特定class1的元素中的class2子元素，注意.class1與.class2中間隔了㇐個空白
  • #id1 .class2：指向文件中id為id1的元素中的class為class2子元素
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Selector Example Example description
.class .intro Selects all elements with class=“intro”
.class1.class2 .name1.name2 Selects all elements with both name1 and name2 set within its class attribute
.class1 .class2 .name1 .name2 Selects all elements with name2 that is a descendant of an element with name1
#id #firstname Selects the element with id=“firstname”
* * Selects all elements
element p Selects all <p> elements
element.class p.intro Selects all <p> elements with class=“intro”
element,element div, p Selects all <div> elements and all <p> elements
element element div p Selects all <p> elements inside <div> elements
element>element div > p Selects all <p> elements where the parent is a <div> element
element+element div + p Selects all <p> elements that are placed immediately after <div> elements
element1~element2 p ~ ul Selects every <ul> element that are preceded by a <p> element
[attribute] [target] Selects all elements with a target attribute
[attribute=value] [target=_blank] Selects all elements with target=“_blank”
[attribute~=value] [title~=flower] Selects all elements with a title attribute containing the word “flower”
`[attribute =value]` `[lang
[attribute^=value] a[href^="https"] Selects every <a> element whose href attribute value begins with “https”
[attribute$=value] a[href$=".pdf"] Selects every <a> element whose href attribute value ends with “.pdf”
[attribute*=value] a[href*="w3schools"] Selects every <a> element whose href attribute value contains the substring “w3schools”
:active a:active Selects the active link
::after p::after Insert something after the content of each <p> element
::before p::before Insert something before the content of each <p> element
:checked input:checked Selects every checked <input> element
:default input:default Selects the default <input> element
:disabled input:disabled Selects every disabled <input> element
:empty p:empty Selects every <p> element that has no children (including text nodes)
:enabled input:enabled Selects every enabled <input> element
:first-child p:first-child Selects every <p> element that is the first child of its parent
::first-letter p::first-letter Selects the first letter of every <p> element
::first-line p::first-line Selects the first line of every <p> element
:first-of-type p:first-of-type Selects every <p> element that is the first <p> element of its parent
:focus input:focus Selects the input element which has focus
:fullscreen :fullscreen Selects the element that is in full-screen mode
:hover a:hover Selects links on mouse over
:in-range input:in-range Selects input elements with a value within a specified range
:indeterminate input:indeterminate Selects input elements that are in an indeterminate state
:invalid input:invalid Selects all input elements with an invalid value
:lang(language) p:lang(it) Selects every <p> element with a lang attribute equal to “it” (Italian)
:last-child p:last-child Selects every <p> element that is the last child of its parent
:last-of-type p:last-of-type Selects every <p> element that is the last <p> element of its parent
:link a:link Selects all unvisited links
:not(selector) :not(p) Selects every element that is not a <p> element
:nth-child(n) p:nth-child(2) Selects every <p> element that is the second child of its parent
:nth-last-child(n) p:nth-last-child(2) Selects every <p> element that is the second child of its parent, counting from the last child
:nth-last-of-type(n) p:nth-last-of-type(2) Selects every <p> element that is the second <p> element of its parent, counting from the last child
:nth-of-type(n) p:nth-of-type(2) Selects every <p> element that is the second <p> element of its parent
:only-of-type p:only-of-type Selects every <p> element that is the only <p> element of its parent
:only-child p:only-child Selects every <p> element that is the only child of its parent
:optional input:optional Selects input elements with no “required” attribute
:out-of-range input:out-of-range Selects input elements with a value outside a specified range
::placeholder input::placeholder Selects input elements with the “placeholder” attribute specified
:read-only input:read-only Selects input elements with the “readonly” attribute specified
:read-write input:read-write Selects input elements with the “readonly” attribute NOT specified
:required input:required Selects input elements with the “required” attribute specified
:root :root Selects the document’s root element
::selection ::selection Selects the portion of an element that is selected by a user
:target #news:target Selects the current active #news element (clicked on a URL containing that anchor name)
:valid input:valid Selects all input elements with a valid value
:visited a:visited Selects all visited links

以上表格取自：https://www.w3schools.com/cssref/css_selectors.asp