Octal literals are not allowed because disallowing them discourages programmers from using leading zeros as padding in a script. For example, look at the following snippet: var eight = 0008, nine = 00009, ten = 000010, eleven = 011; console.log(eight, nine, ten, eleven); Seems harmless enough, right? We programmers with OCD just want to align … Read more
Validate the data before inserting it into your database. If a string is too big to fit in your table, either your column is too narrow, or the data is invalid. You need to decide whether you truncate it before storing it, do some error reporting, or both. Do not turn off the safety features … Read more
In index.js change <React.StrictMode><App /><React.StrictMode> to <App /> and you will not see this warning. Please note that strict mode helps you with Identifying components with unsafe lifecycles Warning about legacy string ref API usage Warning about deprecated findDOMNode usage Detecting unexpected side effects Detecting legacy context API Please refer to https://reactjs.org/docs/strict-mode.html before removing it.
React StrictMode calls all Effects twice to make sure their cleanup/unmount handlers work as intended. You may need to change your effects accordingly, even if they have an empty dependency list and would normally not unmount before the site is closed. Note, this only happens in Strict + development mode. In a production build, effects … Read more
Its main purpose is to do more checking. Just add “use strict”; at the top of your code, before anything else. For example, blah = 33; is valid JavaScript. It means you create a completely global variable blah. But in strict mode it’s an error because you did not use the keyword “var” to declare … Read more
It’s Chrome’s own incorrect behavior that is deprecated, and they’re warning authors to stop relying on it. The scrolling viewport is represented by document.documentElement (<html>) in standards mode or <body> in quirks mode. (Quirks mode emulates the document rendering of Navigator 4 and Explorer 5.) Chrome uses body.scrollTop to represent the viewport’s scroll position in … Read more
The delete statement is still allowed in strict mode, but some particular uses of it are erroneous. It’s only allowed for object properties, not simple names, and only for object properties that can be deleted. Thus var a = {x: 0}; delete a.x; is fine, but delete Object.prototype; is not, and neither is delete a; … Read more
No, you can’t disable strict mode per function. It’s important to understand that strict mode works lexically; meaning — it affects function declaration, not execution. Any function declared within strict code becomes a strict function itself. But not any function called from within strict code is necessarily strict: (function(sloppy) { “use strict”; function strict() { … Read more
In ES5, you can get a reference to global object from within strict mode via indirect eval call: “use strict”; var global = (1,eval)(‘this’); Take a look at my article; particularly at this section on strict mode.