导航
×
   ❮   
HTML CSS JavaScript PHP Go Sass W3C Colors ECMS

JS 参考手册

JS 参考手册(字母排序)

JavaScript

JS Arrays JS Boolean JS Classes JS Dates JS Error JS Global JS Iterators JS JSON JS Maps JS Math JS Numbers JS Objects JS Operators JS Assignment JS Arithmetic JS Comparison JS Logical Operators JS Bitwise Operators JS Misc Operators JS Precedence JS Promises JS RegExp Patterns JS RegExp Reference JS Sets JS Statements JS Strings JS Typed Arrays JS Typed Reference

Window

Window Object Window Console Window History Window Location Window Navigator Window Screen

HTML DOM

HTML Documents HTML Elements HTML Attributes HTML Collection HTML NodeList HTML DOMTokenList 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 HTML Event Objects HTML Event Properties HTML Event Methods

Web APIs

API Canvas API Console API Fetch API Fullscreen API Geolocation API History API MediaQueryList API Storage API Validation API Web

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>

HTML DOM console.assert() 方法


实例

仅当第一个参数为 false 时才向控制台写入消息:

console.assert(document.getElementById("demo"), "You have no element with ID 'demo'");
亲自试一试 »

定义和用法

console.assert() 方法将一条消息写入控制台,但前提是表达式的计算结果为 false。


浏览器支持

表中的数字表示支持该方法的第一个浏览器版本。

方法
console.assert() Yes Yes 28 Yes Yes

语法

console.assert(expression, message)

参数值

参数 类型 描述
expression 布尔表达式 必需。任何表达式。如果表达式的计算结果为 false,则将消息写入控制台。
message 字符串或对象 必需。要在控制台中写入的消息或对象。

更多实例

实例

向控制台写入一个对象:

var myObj = { firstname : "John", lastname : "Doe" };
console.assert(document.getElementById("demo"), myObj);
亲自试一试 »

实例

将数组写入控制台:

var myArr = ["Orange", "Banana", "Mango", "Kiwi" ];
console.assert(document.getElementById("demo"), myArr);
亲自试一试 »

Copyright ©2026 蒙ICP备2026009383号 All Rights Reserved 提供的内容仅用于学习和测试,不保证内容的正确性。