AI代码解释 constobj={[Symbol.toPrimitive](hint){console.log(hint);if(hint=='number'){return1;}if(hint=='string'){return'yan';}returntrue;},};console.log(obj==1);// obj 返回 trueconsole.log(obj=='1');// obj 返回 tru
JavaScript 中数组去重的方法有很多,但是每种方法绕不过的就是判断元素的相等。由于 JS 动态数据类型与隐式转换的关系,判断相等时会有一些特性的不同。有时候生硬的去记忆效果不好,不如从数组去重的例子中学习会有更好的理解。 JavaScript 数据类型有:字符串(string),数值(number),布尔(boolean),undefined,null,引...
semantically oriented definitions of character or string equality and collating order defined in the Unicode specification. Therefore String values that are canonically equal according to the Unicode standard could test as unequal. In effect
// Equality and relational operators test whether two values are equal, // unequal, less than, greater than, and so on. They evaluate to true or false. let x = 2, y = 3; // These = signs are assignment, not equality tests x === y // => false: equality x !== y // => ...
console.log(re.test('example test')); 按照大家对于正则的理解,上面的返回结果应该是true true 先来看看在控制台上运行以上代码的结果: 最后代码运行的结果和我们的预期结果不一致,导致这样的结果是因为在JS的RegExp中存在一个lastIndex属性。 只有正则表达式使用了表示全局检索的 "g" 标志时,该属性才会起作用。
When the equality operator in JavaScript 1.1 attempted to convert a string to a number and failed, it displayed an error message noting that the string could not be converted, instead of converting the string to NaN and returning false as the result of the comparison. This bug has been fixed...
1、对于string,number等基础类型，==和===是有区别的1）不同类型间比较，==之比较“转化成同一类型...
"your name"被称为字符串字面量(string literal)。 字符串文字或字符串是用单引号或双引号括起来的一系列零个或多个字符。 与其他一些编程语言不同的是,单引号和双引号的功能在 JavaScript 中是相同的。 字符串在开头和结尾都要有相同的引号,如果在中间使用了相同的引号,字符串会提前中止并抛出错误。
test("equality matchers", () => { expect(2*2).toBe(4); expect(4-2).not.toBe(1); }) #2) Truthiness Here we will see, matchers for null, falsy, and truthy i.e. false and truth values. It’s important to note that anything that’s not logically true is falsy. ...
Testing String Containment with Regular Expressionsfor using regular expressions to test string containment. Testing String Containment with Regular Expressions Problem You want to use regular expressions to know whether one string contains another.