// ES6 CodeletisValid=true;if(isValid){letnumber=10;console.log('inside:',number);// inside: 10}console.log('outside:',number);// Uncaught ReferenceError: number is not defined 如上述代码所示,使用let分别在if块内、if块外声明了n
consthome="c:\\temp"; 也可以在换行之前加上反斜杠以转义换行。这样反斜杠和换行都不会出现在字符串的值中。 js conststr="this string \ is broken \ across multiple \ lines.";console.log(str);// this string is broken across multiple lines....
functionisPalindrome(word){constlength=word.length;consthalf=Math.floor(length/2);for(letindex=0;index`< half; index++) { if (word[index] !== word[length - index - 1]) { return false; } } return true;}isPalindrome('madam'); // =>`trueisPalindrome('hello');// => false var声...
We then use "if not" (!) to check if the player has entered a valid choice. If choice is null, undefined, or an empty string, the condition inside the first if statement is true, and the code inside the block is executed. Therefore, the output to the console is "You didn't ...
“Control character in string: {a}.” : “在字符串中出现了Control的字符”, “Avoid \\’.” : “避免 \\”, “Avoid \\v.” : “避免 \\v”, “Avoid \\x-.” : “避免 \\x-”, “Bad escapement.” : “错误的转义字符”, ...
Object.create(null).hasOwnProperty('name')// Uncaught TypeError: Object.create(...).hasOwnProperty is not a function Object.hasOwn 不用担心,我们可以使用“Object.hasOwn”来规避这两个问题,比“obj.hasOwnProperty”方法更方便、更安...
let stringNumber ="123"; let convertedNumber = +stringNumber;// convertedNumber is now the number 123 虽然这是一种将字符串转换为数字的简便方法,但也存在一些缺陷,以下是其中一些 前导零:不同于 parseInt(),如果你赋予它整数以外的内容,它可能无法正常工作。
For starters, let’s be clear on something here: Providing a string as the first argument tosetTimeoutorsetIntervalisnotitself a mistake per se. It is perfectly legitimate JavaScript code. The issue here is more one of performance and efficiency. What is often overlooked is that if you pass...
booleanTrue if the string is empty; otherwise false. Usage An empty string has a length of 0. For an empty string,s==""is true, buts==nullis false. Examples (1) This example returns the content ofcities. var cities = "Paris"; // Should not be empty if (cities.isEmpty()) { re...
The following example returns a string for display by the caller:HTML Copy window.displayTickerAlert2 = (symbol, price) => { if (price < 20) { alert(`${symbol}: $${price}!`); return "User alerted in the browser."; } else { return "User NOT alerted."; ...