如果时间小于 10:00,则生成问候 "Good morning",如果时间大于 10:00 小于 20:00,则生成问候 "Good day",否则生成问候 "Good evening": if (time<10) { document.write("早上好"); } else if (time>=10 && time<20) { document.write("今天好"); } else { document.write("晚上好!"); } x的...
Javascript Statement if Javascript examples for Statement:if HOME Javascript Statement if
语句(Statement)—— 表达式加上特定的标识符、关键字、符号形成一定的结构 表达式(Expression) 关键字(Keyword) 语法符(Punctuator) 结构化(Structure)—— 帮助我们组织、分块、分成不同的复用结构 函数(Function) 类(Class) 过程(Process)—— PASCAL 语言就会有 Process 的概念 命名空间(Namespace)—— C++ / ...
When you write code, you will often need to use conditional statements, such as "if" statements. Here's an explanation of the JavaScript If statement.A conditional statement refers to a piece of code that does one thing based on one condition, and another based on another condition. In ...
if (condition) { statements to execute } When JavaScript encounters an if statement, it checks the condition. If and only if, it is found to be true, the statements enclosed within the curly braces are executed. Note, the condition is always enclosed by a pair of parenthesis. Let’s lo...
例如,如下的代码将在控制台输出 5,因为 x 的作用域是声明了 x 的那个函数(或全局范围),而不是 if 语句块。 如果使用 ECMAScript 6 中的 let 声明,上述行为将发生变化。 「变量提升」JavaScript 变量的另一个不同寻常的地方是,你可以先使用变量稍后再声明变量而不会引发异常。这一概念称为变量提升;JavaScript...
Start the script by instantiating the Date() object and assigning it to a constant named “date“. We then access the date objects “getDay()” function to get the day of the week and store it in a variable called “day“. Finally, we use our JavasScript’s if statement to check ...
This JavaScript tutorial explains how to use the if-else statement with syntax and examples. In JavaScript, the if-else statement is used to execute code when a condition is TRUE, or execute different code if the condition evaluates to FALSE.
Use theelse ifstatement to specify a new condition if the first condition is false. Syntax if(condition1) { //block of code to be executed if condition1 is true }elseif(condition2) { //block of code to be executed if the condition1 is false and condition2 is true ...
参考链接:All about IF statements and booleans in JavaScript! – Code The Web What is an if statement? In essence, an if statement simply executes some code if a value is equivalent to true. The if statement syntax if(true){alert('Yay!');} ...