How to enable centered scaling on canvas using FabricJS?

There is an essential difference between JavaScript's WebWorkers and JavaThreads in concurrent processing. 1. JavaScript adopts a single-thread model. WebWorkers is an independent thread provided by the browser. It is suitable for performing time-consuming tasks that do not block the UI, but cannot operate the DOM; 2. Java supports real multithreading from the language level, created through the Thread class, suitable for complex concurrent logic and server-side processing; 3. WebWorkers use postMessage() to communicate with the main thread, which is highly secure and isolated; Java threads can share memory, so synchronization issues need to be paid attention to; 4. WebWorkers are more suitable for front-end parallel computing, such as image processing, and

CompositionAPI in Vue3 is more suitable for complex logic and type derivation, and OptionsAPI is suitable for simple scenarios and beginners; 1. OptionsAPI organizes code according to options such as data and methods, and has clear structure but complex components are fragmented; 2. CompositionAPI uses setup to concentrate related logic, which is conducive to maintenance and reuse; 3. CompositionAPI realizes conflict-free and parameterizable logical reuse through composable functions, which is better than mixin; 4. CompositionAPI has better support for TypeScript and more accurate type derivation; 5. There is no significant difference in the performance and packaging volume of the two; 6.

Use document.createElement() to create new elements; 2. Customize elements through textContent, classList, setAttribute and other methods; 3. Use appendChild() or more flexible append() methods to add elements to the DOM; 4. Optionally use insertBefore(), before() and other methods to control the insertion position; the complete process is to create → customize → add, and you can dynamically update the page content.

TypeScript's advanced condition types implement logical judgment between types through TextendsU?X:Y syntax. Its core capabilities are reflected in the distributed condition types, infer type inference and the construction of complex type tools. 1. The conditional type is distributed in the bare type parameters and can automatically split the joint type, such as ToArray to obtain string[]|number[]. 2. Use distribution to build filtering and extraction tools: Exclude excludes types through TextendsU?never:T, Extract extracts commonalities through TextendsU?T:Never, and NonNullable filters null/undefined. 3

Microfrontendssolvescalingchallengesinlargeteamsbyenablingindependentdevelopmentanddeployment.1)Chooseanintegrationstrategy:useModuleFederationinWebpack5forruntimeloadingandtrueindependence,build-timeintegrationforsimplesetups,oriframes/webcomponents

To get the length of a JavaScript array, you can use the built-in length property. 1. Use the .length attribute to return the number of elements in the array, such as constfruits=['apple','banana','orange'];console.log(fruits.length);//Output: 3; 2. This attribute is suitable for arrays containing any type of data such as strings, numbers, objects, or arrays; 3. The length attribute will be automatically updated, and its value will change accordingly when elements are added or deleted; 4. It returns a zero-based count, and the length of the empty array is 0; 5. The length attribute can be manually modified to truncate or extend the array,

varisfunction-scoped,canbereassigned,hoistedwithundefined,andattachedtotheglobalwindowobject;2.letandconstareblock-scoped,withletallowingreassignmentandconstnotallowingit,thoughconstobjectscanhavemutableproperties;3.letandconstarehoistedbutnotinitial

Proxy and Reflect API are powerful tools used in JavaScript to intercept and customize object operations; 1. Proxy blocks operations such as get, set by wrapping target objects and defining "traps", and implements functions such as logs, verification, read-only control; 2. Reflect provides methods corresponding to Proxy traps to ensure the consistency and correctness of default behaviors and improve code maintainability; 3. Practical applications include Vue3 responsive system, data verification, debug logs, immutable objects and API simulation; 4. Pay attention to performance overhead, complex behavior of built-in objects, this binding problems, and nested objects need to be recursively proxyed; 5. Reasonable use can build efficient, debugable, and reactive