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 trueconsole.log(obj==true);// obj 返回 true 非严格相等并非带来...
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
消息 Warning: SyntaxError: test for equality (==) mistyped as assignment (=)? 错误类型 SyntaxError只在严格模式下会出现的警告。 什么地方出错了? 在通常期望进行相等判定(==)的地方出现了赋值(=)。 为了帮助调试,JavaScript(在开启严格模式的情况下)会对这种情况进行警告。 示例 条件表达式内的赋值 不建议...
// 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
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...
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. ...
import javascript from StrictEqualityTest eq, DataFlow::AnalyzedNode nd, NullLiteral null where eq.hasOperands(nd.asExpr(), null) and not nd.getAValue().isIndefinite(_) and not nd.getAValue() instanceof AbstractNull select eq, "Spurious null check." To paraphrase, the query looks for e...