...1) if … else 语句 if … else 语句的语法: if [ expression ] then Statement(s) to be executed if expression...= b ] then echo “a is not equal to b” fi 运行结果: a is not equal to b 2) if … else … fi 语句 if … else … fi...(s) to be executed if expression...
y);// calling function `foo` with parameters `x` and `y`obj.bar(3);// calling method `bar` of object `obj`// A conditional statementif(x===0){// Is `x` equal to zero?x=123;}// Defining function `baz` with parameters `a` and ...
query('SELECT * FROM boroughs', (error, result) => { if(error) throw error; res.send(result); }); }); router.get('/:id', (req, res) => { const id = req.params.id; pool.query('SELECT name, state FROM boroughs WHERE id = ?', id, (error, result) => { if(error) thro...
if ... else if ... 语句是 if ... else 的高级形式,可让JavaScript根据多种条件做出正确的决定。 if(expression1){Statement(s)to be executedifexpression1istrue}elseif(expression2){Statement(s)to be executedifexpression2istrue}elseif(expression3){Statement(s)to be executedifexpression3istrue}el...
1. if语句 2.switch选择控制语句 3. for 语句 4. while 循环 5. 异常处理 一、JS基础知识 1. js引用 <!--Mathod 1--><!--Mathod 2-->statement 2. Javascript构成 ECMASript: 核心部分,包含js的语法 DOM: 文件对象模型 (整合HTML, CSS, JS) BOM: ...
How the JavaScript if statement works The if statement is the foundation for the if else statement as well as the “if, else if” statement. The “if” statement allows the programmer to execute a set of instructions if a condition is true. If the condition is false, then the code will...
process.nextTick,Promise.then(), MutaionObserver 就属于微任务。 简单概括一下事件循环,就是: 1.执行宏任务队列中第一个任务,执行完后移除它 2.执行所有的微任务,执行完后移除它们 3.执行下一轮宏任务(重复步骤 2) 如此循环就形成了 event loop,其中,每轮执行一个宏任务和所有的微任务。
Iftrue, the loop will start over again, otherwise it ends. JavaScript Loop Statements StatementDescription breakBreaks out of a loop continueSkips a value in a loop whileLoops a code block while a condition is true do...whileLoops a code block once, and then while a condition is true ...
Use theifstatement to specify a block of JavaScript code to be executed if a condition is true. Syntax if(condition) { //block of code to be executed if the condition is true } Note thatifis in lowercase letters. Uppercase letters (If or IF) will generate a JavaScript error. ...
But what if we were to do this: deletesecondObj.name; We’d then get: console.log(secondObj.name);// -> Results in 'undefined' But wouldn’t it be nicer for this to revert to ‘default’? This can easily be done if we modify the original code to leverage prototypal inheritance, ...