HTML DOM Document querySelector() harshe

Definition and usage

querySelector() The method returns elements that match the CSS selectorFirstelements.

To returnAllmatches (not just the first match), please use querySelectorAll().

If the selector is invalid, then querySelector() He querySelectorAll() will throw SYNTAX_ERR Exception.

Example

Example 1

Get the first <p> element:

document.querySelector("p");

Try it yourself

Example 2

Get the first element with class="example":

document.querySelector(".example");

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Example 3

Get the first <p> element with class="example":

document.querySelector("p.example");

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Example 4

Change the text of the element with id="demo":

document.querySelector("#demo").innerHTML = "Hello World!";

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Example 5

Select the first <p> element whose parent element is the <div> element:

document.querySelector("div > p");

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Example 6

Select the first <a> element with the "target" attribute:

document.querySelector("a[target]");

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Example 7

Select the first <h3> or the first <h4>:

<h3>A h3 element</h3>
<h4>A h4 element</h4>
document.querySelector("h3, h4").style.backgroundColor = "red";

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Example 8

Select the first <h3> or the first <h4>:

<h4>A h4 element</h4>
<h3>A h3 element</h3>
document.querySelector("h3, h4").style.backgroundColor = "red";

Try it yourself

Syntax

document.querySelector(cssSelectors)

Parameter

Parameter Description
cssSelectors

Mandatory. A ko manyan CSS selector.

CSS selector a raiwa da HTML element a raiwa id, class, type, attribute, value da sauransu.

Don tsarin yanki na kaiyawa, ka ci gaba da CSS Selectors Kita.

Da a raiwa tsa manyan selector, ka tsama kuma tsa gargareshi (ka tsama da shaidar da yana shida).

Return value

Type Description
Object

Nodelist da a raiwa tsa babban element da a raiwa da CSS selector.

Idan anoma na a raiwa, a raiwa akaiwa null.

Firawsun HTMLCollection da NodeList tsa

NodeList He HTMLcollection Feichang xiangsi。

Shi liang ge dou shi cong wendan zhong qu chu de jie dian （yuan su）de xiangli bu du de jihui （liebiao）。Kai guan jie dian neng tongguo suoding hao ma （xiaobiao）kan chi jie dian。Ji suoding hao ma zhi yu 0 kaishi。

Shi liang ge dou you length ShuXing，ta fanhui liebiao （jihui）zhong yuan su de shu liang。

HTMLCollection shiWendan yuan suDe jihui.

NodeList shiWendan jie dian（yuan su jie dian, shuXing jie dian he wenben jie dian）de jihui。

HTMLCollection xiangmu kan chi guo ta men de mingcheng, id huo suoding hao ma.

NodeList xiangmu kan chi guo ta men de suoding hao ma.

HTMLCollection zhi yong shiShi shiDe jihui.

Ri chi：Ri guo jia ru <li> yuan su ji dianzai DOM zhong de liebiao, zhe HTMLCollection zhong de liebiao yeqie hui gai bian。

NodeList shi chongxuJingtiDe jihui.

Ri chi：Ri guo jia ru <li> yuan su ji dianzai DOM zhong de liebiao, zhe NodeList zhong de liebiao bu hui gai bian。

getElementsByClassName() He getElementsByTagName() Fangfa dou fanhui shi shi HTMLCollection.

querySelectorAll() Fangfa fanhui jingti NodeList.

childNodes ShuXing fanhui shi shi shi NodeList.

Chulai Zhichi

document.querySelector() Shi DOM Level 1 (1998) TeXing.

Suoyou hua she dui zhi chi chi zhe ta：

Chrome IE Edge Firefox Safari Opera
Chrome IE Edge Firefox Safari Opera
ZhiChi 9-11 ZhiChi ZhiChi ZhiChi ZhiChi

Xiangguan YeMian

Jiaocheng：

CSS Selectors

CSS Selectors Kita

HTML DOM NodeList Kita

QuerySelector Fangfa：

querySelector() Fangfa

querySelectorAll() Fangfa

GetElement Fangfa：

getElementById() Fangfa

getElementsByTagName() Fangfa

getElementsByClassName() Fangfa