// Two slashes start single-line commentsvarx;// declaring a variablex=3+y;// assigning a value to the variable `x`foo(x,y);// calling function `foo` with parameters `x` and `y`obj.bar(3);// calling method `bar`
AI代码解释 VariableDeclaration:not(ExportNamedDeclaration>.declaration)>VariableDeclarator.declarations:matches([init.type="ArrayExpression"],:matches([init.type="CallExpression"],[init.type="NewExpression"])[init.optional!=true][init.callee.type="Identifier"][init.callee.name="Array"],[init.type="...
alert(a); // undefined alert(b); // Can't find variable: b b = 10; var a = 20; 3.2. 三种函数类型 1)函数声明在程序级别或另一函数的函数体: function foo() { // ... } function globalFD() { function innerFD() {} } 2)函数表达式在表达式的位置: var foo = function () { //...
A traditional, old-browser-compliant solution is to simply save your reference tothisin a variable that can then be inherited by the closure, e.g.: Game.prototype.restart=function() {this.clearLocalStorage();constself =this;// Save reference to 'this', while it’s still this!this.timer=...
// 用于找出第一个符合条件的数组成员,如果没有找到返回undefined var ary = [{ id: 1, name: '张三' }, { id: 2, name: '李四' }]; let target = ary.find(item => item.id == 2); console.log(target) let target1 = ary.find(item => item.id == 3); console.log(target1) 1...
find({type: 'User'}); users.should.have.length(3); }); }); # 异步代码 When testing synchronous code, omit the callback and Mocha will automatically continue on to the next test. describe('Array', function() { describe('#indexOf()', function() { it('should return -1 when the...
The typeof Operator You can use the JavaScripttypeofoperator to find the type of a JavaScript variable. Thetypeofoperator returns the type of a variable or an expression: Example typeof""// Returns "string" typeof"John"// Returns "string" ...
Especially in the case of values returned by the REST API response of the server, we may need to know the type of the value or variable before we further code to process it. Using the typeof Operator to Find the Type of Variable typeof is a unary operator in javascript that returns ...
functionisArray(variable){returnArray.isArray(variable);} 04、展平嵌套数组的数组: functionflattenArray(array){returnarray.flat();} 05、生成介于最小值和最大值之间的随机数: functiongetRandomNumber(min, max){returnMath.floor(Math.random() * (max...
Theletkeyword allows you to declare a variable with block scope. Example varx =10; // Here x is 10 { letx =2; // Here x is 2 } // Here x is 10 Try it Yourself » Read more aboutletin the chapter:JavaScript Let. JavaScript const ...