为什么javascript 'if statements‘返回undefined? JavaScript中的if语句并不会返回undefined。if语句是一种条件语句,用于根据条件的真假来执行不同的代码块。if语句的返回值是根据条件表达式的结果来确定是否执行其中的代码块。 在JavaScript中,if语句的条件表达式应该是一个布尔值,即true
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function functionName(arg0, arg1, ... argN) { statements } 1. 2. 3. function sayHi(sName, sMessage) { alert("Hello " + sName + sMessage); } 1. 2. 3. 如何调用函数? 函数可以通过其名字加上括号中的参数进行调用,如果有多个参数。 如果您想调用上例中的那个函数,可以使用如下的代码: sayHi...
英文| https://betterprogramming.pub/5-ways-to-refactor-if-else-statements-in-javascript-functions-2865a4bbfe29 翻译| 小爱 在本文中,我将介绍5种通过不必要的if-else语句来整理代码的方法。我将讨论默认参数,或(||)运算符,空位合并,可选链no-else-returns,和保护子句。 1、默认参数 你知道在使用不一致...
英文| https://betterprogramming.pub/5-ways-to-refactor-if-else-statements-in-javascript-functions-2865a4bbfe29 翻译| 小爱 在本文中,我将介绍5种通过不必要的if-else语句来整理代码的方法。我将讨论默认参数,或(||)运算符,空位合并,可选链no-e...
In JavaScript we have the following conditional statements:Use if to specify a block of code to be executed, if a specified condition is true Use else to specify a block of code to be executed, if the same condition is false Use else if to specify a new condition to test, if the ...
In JavaScript we have the following conditional statements: Useifto specify a block of code to be executed, if a specified condition is true Useelseto specify a block of code to be executed, if the same condition is false Useelse ifto specify a new condition to test, if the first condit...
In the following sections, we'll go over the following five control flow statements in JavaScript: if, else, switch, for and while. The if statement Conditional statements occur in almost all programming languages that we use today. They are simply statements that evaluate a certain condition an...
if( condition ) {// statements} 即使只有一个语句要执行,始终使用大括号是一种很好的编程习惯。这有助于代码更易于阅读并避免许多混淆。 请参阅以下示例: if( condition )statement_1statement_2; 如果不使用花括号,将很难看出 s...
condition_1, condition_2 : Can be any JavaScript expression that evaluates to true or false. Parentheses are required around the condition. If the condition evaluates to true, the statements in statement_1 are executed, otherwise, statement_2 is executed. statements_1, statements_2 : Can be ...