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promise. Parameters of then() . then is a method on promise prototype, which returns a promise object, which can accept two callback parameters: 1 onResolved, 2. Onrejected, these two parameters have one parameter respectively, which is the data of successful execution and the data of failed execution. In fact, the first callback function ...

1, Deconstruction and assignment of variables 1. Deconstruction assignment of object (1) The property name is inconsistent with the variable name When the attribute name is inconsistent with the variable name, you need to explicitly specify the attribute name. In this way, the attribute value can be assigned to the variable. let user = {name ...

sinon As you know, in Java unit testing, when you can't get the actual object, we can use Mock/Stub to mock our code, which is more convenient for us to test. EasyMock, JMock and Mockito can solve these problems. The concepts of spy, stub and mock are introduced. Similarly, we will encounter similar situations in front-end testing. Sinon.js is ...

generator is a special iterator, which can replace the implementation of iterator to make the code more conciseWhat is an iteratorAn iterator is called an iterator. It is an object used to help traverse a data structure. This object needs to comply with the iterator protocol.The iterator protocol requires the implementation of the next method, ...

Node. The events module of JS provides an external EventEmitter object for Node. Events in JS are managed uniformly. Because Node.js uses event-driven mechanisms, and EventEmitter is Node.js implements the foundation of event driven. On the basis of EventEmitter, Node. Almost all modules in JS inherit this class to implement an asynchronous eve ...

ES6 (29) ES6 latest proposal, do, throw, partial function execution, pipeline operator |>, Curitization,:, Realm API 1. do expression Essentially, a block-level scope is a statement that encapsulates multiple operations together with no return value. { let t = f(); t = t * t + 1; } In the code above, the block-level scope encaps ...

1.this point Function has three execution modes: global function, object method and constructorthis: I point to whoever calls me (independent of the function declaration, depending on the function call) Global function: function name () -------------- > this points to windowObject method: object name Method name () ---- -- > this poi ...

Time complexity & space complexityIt can be seen from the figure that the time complexity should be controlled below O(nlogn).Space complexity is a measure of the amount of storage space temporarily occupied by an algorithm during operationAccording to their characteristics, js sorting can be roughly divided into two types: comparison sort ...

brief introduction    array traversal method is also called array iterator method. Iterator is a software design pattern in programming. In js, we can use it to traverse the array without paying attention to the details of its internal implementation.    the following traversal methods will not affect the original array, th ...

Previously: Wechat applet learning journey - production of the first page Wechat applet learning journey - making your own applet based on zero - making the second page Introduction to wechat applet (3) We made the article section earlier. The simulated user collection articles and browsing times we made at that time used png format ...