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JS 参考手册

JS 参考手册（字母排序）

JavaScript

JS Arrays JS Boolean

Boolean() new Boolean() constructor prototype toString() valueOf()

constructor() extends static super

JS Dates JS Error

isError() name message

decodeURI() decodeURIComponent() encodeURI() encodeURIComponent() escape() eval() Infinity isFinite() isNaN() NaN Number() parseFloat() parseInt() String() undefined unescape()

drop() every() filter() find() flatMap() forEach() map() reduce() some() take()

parse() stringify()

new Map clear() delete() entries() forEach() get() groupBy() has() keys() set() size values()

JS Math JS Numbers JS Objects JS Operators JS Assignment

Assign Simple Assign Add Assign Subtract Assign Multiply Assign Divide Assign Remainder Assign Colon Assign AND Assign OR Assign Nullish

Addition Subtraction Multiplication Division Exponentiation Remainder Increment Decrement Concatenation Unary Plus Unary Negation

Equal Strict Equal Not Equal Strict Not Equal Greater Than Less Than Greater Equal Less Equal

JS Logical Operators

Logical AND Logical OR Logical NOT Logical Nullish

JS Bitwise Operators

Bitwise AND Bitwise OR Bitwise NOT Bitwise XOR Bitwise Left Bitwise Right Bitwise Signed

JS Misc Operators

: ?. ... () ? x : y => delete in instanceof typeof void

JS Precedence JS Promises

all() allSettled() any() catch() finally() race() reject() resolve() then()

JS RegExp Patterns

/d /g /i /m /s /u /v /y [a] [^a] [abc] [^abc] [A-Z] [^A-Z] [0-9] [^0-9] a|b . \w \W \d \D \s \S [\b] \0 \n \f \r \t \v \p \P \ddd \xdd \udddd ^ $ \b \B x(?=y) x(?!y) (?<=y)x (?<!y)x (x) (?<name>x) (?flags:x) + * ? {n} {n,m} {n,}

JS RegExp Reference

compile() constructor dotAll escape() exec() flags global hasIndices ignoreCase lastIndex multiline source sticky test() toString() unicode unicodeSets

new Set add() clear() delete() difference() entries() forEach() has() intersection() isDisjointFrom() isSubsetOf() isSupersetOf() keys() size symmetricDifference() union() values()

break class const continue debugger do...while for for...in for...of function if...else let return switch throw try...catch var while

JS Strings JS Typed Arrays

Int8Array Uint8Array Uint8ClampedArray Int16Array Uint16Array Int32Array Uint32Array BigInt64Array Float16Array Float32Array Float64Array BigUint64Array

JS Typed Reference

Window

Window Object Window Console

assert() clear() count() error() group() groupCollapsed() groupEnd() info() log() table() time() timeEnd() trace() warn()

back() forward() go() length

Window Location

assign() hash host hostname href origin pathname port protocol reload() replace() search

Window Navigator

appCodeName appName appVersion cookieEnabled geolocation javaEnabled() language onLine platform product taintEnabled() userAgent

availHeight availWidth colorDepth height pixelDepth width

HTML DOM

HTML Documents HTML Elements

accessKey addEventListener() after() append() appendChild() attributes before() blur() childElementCount childNodes children classList className click() clientHeight clientTop clientWidth cloneNode() closest() compareDocumentPosition() contains() contentEditable dir firstChild firstElementChild focus() getAttribute() getAttributeNode() getBoundingClientRect() getElementsByClassName() getElementsByTagName() hasAttribute() hasAttributes() hasChildNodes() id innerHTML innerText insertAdjacentElement() insertAdjacentHTML() insertAdjacentText() insertBefore() isContentEditable isDefaultNamespace() isEqualNode() isSameNode() isSupported() lang lastChild lastElementChild matches() namespaceURI nextSibling nextElementSibling nodeName nodeType nodeValue normalize() offsetHeight offsetWidth offsetParent offsetTop outerHTML outerText ownerDocument parentNode parentElement previousSibling previousElementSibling querySelector() querySelectorAll() remove() removeAttribute() removeAttributeNode() removeChild() removeEventListener() replaceChild() scrollHeight scrollIntoView() scrollTop scrollWidth setAttribute() setAttributeNode() style tabIndex tagName textContent title clientLeft offsetLeft scrollLeft

HTML Attributes

getNamedItem() isId item() length name removeNamedItem() setNamedItem() specified value

HTML Collection

item() length namedItem()

entries() forEach() item() keys() length values()

HTML DOMTokenList

add() contains() entries() forEach() item() keys() length remove() replace() supports() toggle() value values()

alignContent alignItems alignSelf animation animationDelay animationDirection animationDuration animationFillMode animationIterationCount animationName animationTimingFunction animationPlayState background backgroundAttachment backgroundClip backgroundColor backgroundImage backgroundOrigin backgroundPosition backgroundRepeat backgroundSize backfaceVisibility border borderBottom borderBottomColor borderBottomLeftRadius borderBottomRightRadius borderBottomStyle borderBottomWidth borderCollapse borderColor borderImage borderImageOutset borderImageRepeat borderImageSlice borderImageSource borderImageWidth borderLeft borderLeftColor borderLeftStyle borderLeftWidth borderRadius borderRight borderRightColor borderRightStyle borderRightWidth borderSpacing borderStyle borderTop borderTopColor borderTopLeftRadius borderTopRightRadius borderTopStyle borderTopWidth borderWidth bottom boxShadow boxSizing captionSide caretColor clear clip color columnCount columnFill columnGap columnRule columnRuleColor columnRuleStyle columnRuleWidth columns columnSpan columnWidth counterIncrement counterReset cssFloat cursor direction display emptyCells filter flex flexBasis flexDirection flexFlow flexGrow flexShrink flexWrap font fontFamily fontSize fontStyle fontVariant fontWeight fontSizeAdjust height isolation justifyContent left letterSpacing lineHeight listStyle listStyleImage listStylePosition listStyleType margin marginBottom marginLeft marginRight marginTop maxHeight maxWidth minHeight minWidth objectFit objectPosition opacity order orphans outline outlineColor outlineOffset outlineStyle outlineWidth overflow overflowX overflowY padding paddingBottom paddingLeft paddingRight paddingTop pageBreakAfter pageBreakBefore pageBreakInside perspective perspectiveOrigin position quotes resize right scrollBehavior tableLayout tabSize textAlign textAlignLast textDecoration textDecorationColor textDecorationLine textDecorationStyle textIndent textOverflow textShadow textTransform top transform transformOrigin transformStyle transition transitionProperty transitionDuration transitionTimingFunction transitionDelay unicodeBidi userSelect verticalAlign visibility width wordBreak wordSpacing wordWrap widows zIndex

HTML Events

onabort onafterprint animationend animationiteration animationstart onbeforeprint onbeforeunload onblur oncanplay oncanplaythrough onchange onclick oncontextmenu oncopy oncut ondblclick ondrag ondragend ondragenter ondragleave ondragover ondragstart ondrop ondurationchange onended onerror onfocus onfocusin onfocusout fullscreenchange fullscreenerror onhashchange oninput oninvalid onkeydown onkeypress onkeyup onload onloadeddata onloadedmetadata onloadstart onmessage onmousedown onmouseenter onmouseleave onmousemove onmouseover onmouseout onmouseup onoffline ononline onopen onpagehide onpageshow onpaste onpause onplay onplaying onprogress onratechange onresize onreset onscroll onsearch onseeked onseeking onselect onshow onstalled onsubmit onsuspend ontimeupdate ontoggle touchcancel touchend touchmove touchstart transitionend onunload onvolumechange onwaiting onwheel

HTML Event Objects

Animation Events Clipboard Events Drag Events Events Focus Events HashChange Events Input Events Keyboard Events Mouse Events PageTransition Events PopState Events Progress Events Storage Events Touch Events Transition Events Ui Events Wheel Events

HTML Event Properties HTML Event Methods

getModifierState() preventDefault() stopImmidiatePropagation() stopPropagation()

Web APIs

API Canvas API Console API Fetch API Fullscreen

exitFullscreen() fullscreenElement fullscreenEnabled() requestFullscreen()

API Geolocation

coordinates getCurrentPosition() position

API History API MediaQueryList API Storage

clear() getItem() key() length removeItem() setItem()

API Validation API Web

crypto.getRandomNumber()

HTML 对象

<a> <abbr> <address> <area> <article> <aside> <audio> <b> <base> <bdo> <blockquote> <body> <br> <button> <canvas> <caption> <cite> <code> <col> <colgroup> <datalist> <dd> <del> <details> <dfn> <dialog> <div> <dl> <dt> <em> <embed> <fieldset> <figcaption> <figure> <footer> <form> <head> <header> <h1> - <h6> <hr> <html> <i> <iframe> <img> <ins> <input> button <input> checkbox <input> color <input> date <input> datetime <input> datetime-local <input> email <input> file <input> hidden <input> image <input> month <input> number <input> password <input> radio <input> range <input> reset <input> search <input> submit <input> text <input> time <input> url <input> week <kbd> <label> <legend> <li> <link> <map> <mark> <menu> <menuitem> <meta> <meter> <nav> <object> <ol> <optgroup> <option> <output> <p> <param> <pre> <progress> <q> <s> <samp> <script> <section> <select> <small> <source> <span> <strong> <sub> <summary> <sup> <table> <tbody> <td> <tfoot> <th> <thead> <tr> <textarea> <time> <title> <track> <u> <ul> <var> <video>

Storage length 属性

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实例

获取此域的本地存储项数:

var x = localStorage.length;

亲自试一试 »

定义和用法

length 属性返回存储在浏览器 Storage 对象中的项目数，对于这个特定的域。

length 属性属于 Storage 对象，它可以是 localStorage 对象，也可以是 sessionStorage 对象。

浏览器支持

属性
length	4	8	3.5	4	10.5

语法

localStorage.length;

Or:

sessionStorage.length;

技术细节

DOM 版本:	Web Storage API
返回值:	整数，表示存储项目的数量。

更多实例

实例

相同的例子，但使用会话存储而不是本地存储。

获取此域的会话存储项数:

var x = sessionStorage.length;

亲自试一试 »

实例

循环遍历每个本地存储项并显示名称:

for (i = 0; i< localStorage.length; i++) {
x = localStorage.key(i);
document.getElementById("demo").innerHTML += x;
}

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