If the function exist, the typeof operator will return the string“function”:Javascript typeof operator1 2 3 4 5 6 7 function test() { console.log('Welcome to W3Docs'); } //Call the function above if it exists. if (typeof test === "function") { test(); }...
const createDirIfNotExists = dir => (!fs.existsSync(dir) ? fs.mkdirSync(dir) : undefined); createDirIfNotExists('test'); 3.currentURL:返回当前链接url const currentURL = () => window.location.href; currentURL(); // 'https://juejin.im' 4.distance:返回两点间的距离 该代码段通过计算欧几...
arguments, nodelist 等类数组转换成数组的方式有很多种,我第一次看到下面这种 ES5 类数组转数组的方式也是很懵逼。 functiontestArrayLikeToArray { varargs; console.log(arguments);// => { [Iterator] 0: 'a', 1: 'b', 2: 'c', [Symbol(Symbol.iterator)]: [λ: values] } // 可以通过下标...
If a value isn't provided, leaveOpen defaults to false. In JS, use an array buffer or a readable stream to receive the data: Using an ArrayBuffer: JavaScript Copy async function streamToJavaScript(streamRef) { const data = await streamRef.arrayBuffer(); } Using a ReadableStream: ...
consttest={name:'1+1=10',func:function(){returnthis.name;},};console.log(test.func());// 1+1=10consttest2={name:'1+1=2',};test2.func=test.func;console.log(test2.func());// 1+1=2 在函数内部,this的值取决于函数如何被调用。同一个函数,根据其调用的方式,this的值是不同的...
---Table structureforbrowser_frontend_info---IFEXISTS(SELECT*FROMsys.all_objectsWHEREobject_id=OBJECT_ID(N'[dbo].[browser_frontend_info]')ANDtypeIN('U'))DROPTABLE[dbo].[browser_frontend_info]GOCREATETABLE[dbo].[browser_frontend_info]([uuid]varchar(255)COLLATEChinese_PRC_CI_ASNOTNULL,[fing...
A neatly self-contained function can be replaced with a better version at a future time: a standard example would be a "sorting" function. With low numbers of test data items that need to be sorted into order in some sort() function, a simple "bubble sort" might be fine. This runs ...
If a class or component doesn't dispose the DotNetObjectReference, dispose it from the client by calling dispose on the passed DotNetObjectReference:JavaScript Copy window.{JS FUNCTION NAME} = (dotNetHelper) => { dotNetHelper.invokeMethodAsync('{.NET METHOD ID}'); dotNetHelper.dispose(...
//1. unit under test describe('Products Service', function() { describe('Add new product', function() { //2. scenario and 3. expectation it('When no price is specified, then the product status is pending approval', ()=> { const newProduct = new ProductService().add(...); expect...
nbsp;imageExists(e.target.result, function(exists){ ...