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JS 参考手册

JS 参考手册（字母排序）

JavaScript

JS Arrays
Array( ) at() concat() constructor copyWithin() entries() every() fill() filter() find() findIndex() findLast() findLastIndex() flat() flatMap() forEach() from() includes() indexOf() isArray() join() keys() lastIndexOf() length map() of() pop() prototype push() reduce() reduceRight() rest (...) reverse() shift() slice() some() sort() splice() spread (...) toReversed() toSorted() toSpliced() toString() unshift() values() valueOf() with()
JS Boolean
Boolean() new Boolean() constructor prototype toString() valueOf()
JS Classes
constructor() extends static super
JS Dates
new Date() constructor getDate() getDay() getFullYear() getHours() getMilliseconds() getMinutes() getMonth() getSeconds() getTime() getTimezoneOffset() getUTCDate() getUTCDay() getUTCFullYear() getUTCHours() getUTCMilliseconds() getUTCMinutes() getUTCMonth() getUTCSeconds() now() parse() prototype setDate() setFullYear() setHours() setMilliseconds() setMinutes() setMonth() setSeconds() setTime() setUTCDate() setUTCFullYear() setUTCHours() setUTCMilliseconds() setUTCMinutes() setUTCMonth() setUTCSeconds() toDateString() toISOString() toJSON() toLocaleDateString() toLocaleTimeString() toLocaleString() toString() toTimeString() toUTCString() UTC() valueOf()
JS Error
isError() name message
JS Global
decodeURI() decodeURIComponent() encodeURI() encodeURIComponent() escape() eval() Infinity isFinite() isNaN() NaN Number() parseFloat() parseInt() String() undefined unescape()
JS Iterators
drop() every() filter() find() flatMap() forEach() map() reduce() some() take()
JS JSON
parse() stringify()
JS Maps
new Map clear() delete() entries() forEach() get() groupBy() has() keys() set() size values()
JS Math
abs() acos() acosh() asin() asinh() atan() atan2() atanh() cbrt() ceil() clz32() cos() cosh() E exp() expm1() f16round() floor() fround() LN2 LN10 log() log10() log1p() log2() LOG2E LOG10E max() min() PI pow() random() round() sign() sin() sinh() sqrt() SQRT1_2 SQRT2 tan() tanh() trunc()
JS Numbers
constructor EPSILON isFinite() isInteger() isNaN() isSafeInteger() MAX_SAFE_INTEGER MIN_SAFE_INTEGER MAX_VALUE MIN_VALUE NEGATIVE_INFINITY POSITIVE_INFINITY parseFloat() parseInt() prototype toExponential() toFixed() toLocaleString() toPrecision() toString() valueOf() NaN
JS Objects
assign() constructor create() defineProperties() defineProperty() delete entries() freeze() fromEntries() getOwnPropertyDescriptor() getOwnPropertyDescriptors() getOwnPropertyNames() groupBy() isExtensible() isFrozen() isSealed() keys() preventExtensions() prototype seal() toString() valueOf() values()
JS Operators JS Assignment
Assign Simple Assign Add Assign Subtract Assign Multiply Assign Divide Assign Remainder Assign Colon Assign AND Assign OR Assign Nullish
JS Arithmetic
Addition Subtraction Multiplication Division Exponentiation Remainder Increment Decrement Concatenation Unary Plus Unary Negation
JS Comparison
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
JS Sets
new Set add() clear() delete() difference() entries() forEach() has() intersection() isDisjointFrom() isSubsetOf() isSupersetOf() keys() size symmetricDifference() union() values()
JS Statements
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
at() charAt() charCodeAt() codePointAt() concat() constructor endsWith() fromCharCode() includes() indexOf() isWellFormed() lastIndexOf() length localeCompare() match() matchAll() padEnd() padStart() prototype repeat() replace() replaceAll() search() slice() split() startsWith() substr() substring() toLocaleLowerCase() toLocaleUpperCase() toLowerCase() toString() toUpperCase() toWellFormed() trim() trimEnd() trimStart() valueOf()
JS Typed Arrays
Int8Array Uint8Array Uint8ClampedArray Int16Array Uint16Array Int32Array Uint32Array BigInt64Array Float16Array Float32Array Float64Array BigUint64Array
JS Typed Reference
at() byteLength byteOffset bytesPerElement copyWithin() entries() every() fill() filter() find() findIndex() findLast() findLastIndex() forEach() from() includes() indexOf() join() keys() lastIndexOf() length map() name of() reduce() reduceRight() reverse() set() slice() some() sort() subarray() toLocaleString() toReversed() toSorted() toString() values() with()

Window

Window Object
addeventlistener() alert() atob() blur() btoa() clearInterval() clearTimeout() close() closed confirm() console defaultStatus document focus() frameElement frames history getComputedStyle() innerHeight innerWidth length localStorage location matchMedia() moveBy() moveTo() name navigator open() opener outerHeight outerWidth pageXOffset pageYOffset parent print() prompt() removeEventlistener() resizeBy() resizeTo() screen screenTop screenX screenY scrollBy() scrollTo() scrollX scrollY sessionStorage self setInterval() setTimeout() status stop() top screenLeft
Window Console
assert() clear() count() error() group() groupCollapsed() groupEnd() info() log() table() time() timeEnd() trace() warn()
Window History
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
Window Screen
availHeight availWidth colorDepth height pixelDepth width

HTML DOM

HTML Documents
activeElement addEventListener() adoptNode() anchors applets baseURI body charset characterSet close() cookie createAttribute() createComment() createDocumentFragment() createElement() createEvent() createTextNode() defaultView designMode doctype documentElement documentMode documentURI domain domConfig embeds execCommand() forms getElementById() getElementsByClassName() getElementsByName() getElementsByTagName() hasFocus() head images implementation importNode() inputEncoding lastModified links normalize() normalizeDocument() open() querySelector() querySelectorAll() readyState referrer removeEventListener() renameNode() scripts strictErrorChecking title URL write() writeln()
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()
HTML NodeList
entries() forEach() item() keys() length values()
HTML DOMTokenList
add() contains() entries() forEach() item() keys() length remove() replace() supports() toggle() value values()
HTML Styles
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

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
altKey (Mouse) altKey (Key) animationName bubbles button buttons cancelable charCode clientX clientY code ctrlKey (Mouse) ctrlKey (Key) currentTarget data defaultPrevented deltaX deltaY deltaZ deltaMode detail elapsedTime elapsedTime eventPhase inputType isTrusted key keyCode location metaKey (Mouse) metaKey (Key) newURL oldURL offsetX offsetY pageX pageY persisted propertyName relatedTarget relatedTarget screenX screenY shiftKey (Mouse) shiftKey (Key) target targetTouches timeStamp touches type which (Mouse) which (Key) view
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


JavaScript Iterator map() 方法

❮ 上一个 完整 JS 参考 下一个 ❯

示例

返回一个包含所有元素值平方根的新数组:

// 创建一个迭代器
const myIterator = Iterator.from("123456789");

// 映射迭代器
const mappedIterator = myIterator.map(x => x * 2);
亲自试一试 »

描述

map() 会为迭代器中的每个元素调用一个函数，从而创建一个新的迭代器。

map() 不会为空元素执行该函数。

map() 不会更改原始迭代器。

语法

iterator.map(function(currentValue, index, arr), thisValue)

参数

参数 描述
function() 必需。
要对每个迭代器元素运行的函数。
currentValue 必需。
当前元素的值。
index 可选。
当前元素的索引。
arr 可选。
当前元素的数组。
thisValue 可选。
默认值为 undefined。
传递给函数的 this 值。

返回值

类型 描述
迭代器 对迭代器中的每个元素运行函数的结果。

迭代器辅助方法:

drop() 方法

every() 方法

filter() 方法

find() 方法

flatMap() 方法

forEach() 方法

map() 方法

reduce() 方法

reduce() 方法

some() 方法

take() 方法

另请参阅:

完整的 JavaScript 迭代器教程

完整的 JavaScript 迭代器参考

浏览器支持

iterator.map() 是 JavaScript 2025 的一项特性。

ES 2025 自 2025 年 5 月起，所有现代浏览器均已完全支持 ES 2025。

Chrome
136		 Edge
136		 Firefox
129		 Safari
18.2		 Opera
120
2025年4月 2025年4月 2024年8月 2024年12月 2025年5月
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