САМОСТОЯТЕЛЬНОЕ ОБУЧЕНИЕ ДЛЯ ВЕБ РАЗРАБОТЧИКОВ
HTML CSS JAVASCRIPT SQL PYTHON PHP BOOTSTRAP КАК W3.CSS JQUERY JAVA ВСЕ ФОРУМ УПРАЖНЕНИЯ СПРАВОЧНИКИ

JS Справочник

JS по категориям JS по алфавиту

JavaScript

JS Массивы
concat() constructor copyWithin() entries() every() fill() filter() find() findIndex() forEach() from() includes() indexOf() isArray() join() keys() length lastIndexOf() map() pop() prototype push() reduce() reduceRight() reverse() shift() slice() some() sort() splice() toString() unshift() valueOf()
JS Булевы
constructor prototype toString() valueOf()
JS Классы
constructor() extends static super
JS Даты
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 Ошибка
name message
JS Булевы
decodeURI() decodeURIComponent() encodeURI() encodeURIComponent() escape() eval() Infinity isFinite() isNaN() NaN Number() parseFloat() parseInt() String() undefined unescape()
JS JSON
parse() stringify()
JS Математика
abs() acos() acosh() asin() asinh() atan() atan2() atanh() cbrt() ceil() cos() cosh() E exp() floor() LN2 LN10 log() LOG2E LOG10E max() min() PI pow() random() round() sin() sqrt() SQRT1_2 SQRT2 tan() tanh() trunc()
JS Числа
constructor isFinite() isInteger() isNaN() isSafeInteger() MAX_VALUE MIN_VALUE NEGATIVE_INFINITY NaN POSITIVE_INFINITY prototype toExponential() toFixed() toLocaleString() toPrecision() toString() valueOf()
JS Операторы JS Рег.Выражения
constructor compile() exec() g global i ignoreCase lastIndex m multiline n+ n* n? n{X} n{X,Y} n{X,} n$ ^n ?=n ?!n source test() toString() [abc] [^abc] [0-9] [^0-9] (x|y) . \w \W \d \D \s \S \b \B \0 \n \f \r \t \v \xxx \xdd \uxxxx
JS Заявления
break class continue debugger do...while for for...in for...of function if...else return switch throw try...catch var while
JS Строки
charAt() charCodeAt() concat() constructor endsWith() fromCharCode() includes() indexOf() lastIndexOf() length localeCompare() match() prototype repeat() replace() search() slice() split() startsWith() substr() substring() toLocaleLowerCase() toLocaleUpperCase() toLowerCase() toString() toUpperCase() trim() valueOf()

HTML DOM

DOM Атрибута
getNamedItem() isId item() length name removeNamedItem() setNamedItem() specified value
DOM Документа
activeElement addEventListener() adoptNode() anchors applets baseURI body close() cookie charset characterSet createAttribute() createComment() createDocumentFragment() createElement() createEvent() createTextNode() defaultView designMode doctype documentElement documentMode documentURI domain embeds execCommand() forms fullscreenElement fullscreenEnabled() 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()
DOM Элемента
accessKey addEventListener() ДобавитьChild() attributes blur() childElementCount childNodes children classList className click() clientHeight clientLeft clientTop clientWidth cloneNode() compareDocumentPosition() contains() contentEditable dir exitFullscreen() 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 namespaceURI nextSibling nextElementSibling nodeName nodeType nodeValue normalize() offsetHeight offsetWidth offsetLeft offsetParent offsetTop outerHTML outerText ownerDocument parentNode parentElement previousSibling previousElementSibling querySelector() querySelectorAll() remove() removeAttribute() removeAttributeNode() removeChild() removeEventListener() replaceChild() requestFullscreen() scrollHeight scrollIntoView() scrollLeft scrollTop scrollWidth setAttribute() setAttributeNode() style tabIndex tagName textContent title
DOM События
abort afterprint animationend animationiteration animationstart beforeprint beforeunload blur canplay canplaythrough change click contextmenu copy cut dblclick drag dragend dragenter dragleave dragover dragstart drop durationchange ended error focus focusin focusout fullscreenchange fullscreenerror hashchange input invalid keydown keypress keyup load loadeddata loadedmetadata loadstart message mousedown mouseenter mouseleave mousemove mouseover mouseout mouseup offline online open pagehide pageshow paste pause play playing progress ratechange resize reset scroll search seeked seeking select show stalled submit suspend timeupdate toggle touchcancel touchend touchmove touchstart transitionend unload volumechange waiting wheel altKey altKey animationName bubbles button buttons cancelable charCode clientX clientY code createEvent() ctrlKey ctrlKey currentTarget data defaultPrevented deltaX deltaY deltaZ deltaMode detail elapsedTime elapsedTime eventPhase getModifierState() inputType isTrusted key keyCode location metaKey metaKey newURL oldURL pageX pageY persisted preventDefault() propertyName relatedTarget relatedTarget screenX screenY shiftKey shiftKey stopImmediatePropagation() stopPropagation() target targetTouches timeStamp touches type which which view
DOM Объекты событий
AnimationEvent ClipboardEvent DragEvent Event FocusEvent HashChangeEvent InputEvent KeyboardEvent MouseEvent PageTransitionEvent PopStateEvent ProgressEvent StorageEvent TouchEvent TransitionEvent UiEvent WheelEvent
DOM HTML Коллекция
item() length namedItem()
DOM Местоположение
hash host hostname href origin pathname port protocol search assign() reload() replace()
DOM Навигатор
appCodeName appName appVersion cookieEnabled geolocation language onLine platform product userAgent javaEnabled() taintEnabled()
DOM Экран
availHeight availWidth colorDepth height pixelDepth width
DOM Стиль
alignContent alignItems alignSelf animation animationDelay animationDirection animationDuration animationFillMode animationIterationCount animationName animationTimingFunction animationPlayState background backgroundAttachment backgroundColor backgroundImage backgroundPosition backgroundRepeat backgroundClip backgroundOrigin 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 clear clip color columnCount columnFill columnGap columnRule columnRuleColor columnRuleStyle columnRuleWidth columns columnSpan columnWidth counterIncrement counterReset cursor direction display emptyCells filter flex flexBasis flexDirection flexFlow flexGrow flexShrink flexWrap cssFloat 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 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
DOM Окно
closed console defaultStatus document frameElement frames history innerHeight innerWidth length localStorage location name navigator opener outerHeight outerWidth pageXOffset pageYOffset parent screen screenLeft screenTop screenX screenY sessionStorage self status top alert() atob() blur() btoa() clearInterval() clearTimeout() close() confirm() focus() getComputedStyle() matchMedia() moveBy() moveTo() open() print() prompt() resizeBy() resizeTo() scrollBy() scrollTo() setInterval() setTimeout() stop()

Веб APIы

API Консоль
assert() clear() count() error() group() groupCollapsed() groupEnd() info() log() table() time() timeEnd() trace() warn()
API Геолокация
coordinates position
API История
back() forward() go() length
API Место хранения
key() length getItem() setItem() removeItem() clear()

HTML Объекты

<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> <style> <sub> <summary> <sup> <table> <tbody> <td> <tfoot> <th> <thead> <tr> <textarea> <time> <title> <track> <u> <ul> <var> <video>

Другое

Объявление стиля CSS
cssText getPropertyPriority() getPropertyValue() item() length parentRule removeProperty() setProperty()
JS Преобразование


JavaScript Булевы Свойство undefined

❮ Назад JavaScript Глобальные функции Вперед ❯

Пример

Проверьте, определена ли переменная:

var x;

if (typeof x === "undefined") {
  txt = "x является неопределенной";
} else {
  txt = "х является определенной";
}
Попробуйте сами »

Больше примеров "Попробуйте сами" ниже.

Определение и использование

Свойство undefined указывает, что переменной не присвоено значение или она вообще не объявлена.

Поддержка браузера

Свойство
undefined Да Да Да Да Да

Технические детали

Версия JavaScript: ECMAScript 1

Еще примеры

Пример

Проверьте, объявлена ли переменная неопределенной:

if (typeof y === "undefined") {
  txt = "y является неопределенной";
} else {
  txt = "y является определенной";
}
Попробуйте сами »
❮ Назад JavaScript Глобальные функции Вперед ❯