The three reasons were: Readability. A generator is quite different from a function, and the difference should be immediately visible (that is, without examining the whole implementation in search for a yield). Generality. It should be naturally possible to write generators that do not yield, and only return directly. Moreover, commenting out part of the … Read more
Is this just syntactic sugar for ES6? No, it’s more than syntactic sugar. The gory details are buried in ยง13.6.3.9 CreatePerIterationEnvironment. How is this working? If you use that let keyword in the for statement, it will check what names it does bind and then create a new lexical environment with those names for a) … Read more
Use instanceof: var foo = new Set; foo instanceof Set; // True! foo instanceof Map; // False!
ie 11 not support arrow functions try var selectedRoles = vm.roles.filter(function(x) { return x.id === role.id; });
Updated with a solution thanks to feedback from @SimenB on GitHub. Factory function must return a function The factory function must return the mock: the object that takes the place of whatever it’s mocking. Since we’re mocking an ES6 class, which is a function with some syntactic sugar, then the mock must itself be a … Read more
It means that the function returns an iterator (so it can be repeatedly called with .next() to yield more values. check out http://wingolog.org/archives/2013/05/08/generators-in-v8 for more info It’s an ES6 construct, so at the moment you see it more in node rather than client side js
I want to write my Javascript class like below You can’t, in the same way you can’t overload standard functions like that. What you can do is use the arguments object to query the number of arguments passed: class Option { constructor(key, value, autoLoad) { // new Option() if(!arguments.length) { this.autoLoad = false; } // … Read more
Why use const and when to use let in for…of loops? If there are no assignments to the identifier within the loop body, it’s a matter of style whether you use let or const. Use const if you want the identifier within the loop body to be read-only (so that, for instance, if someone modifies … Read more
It seems like you can’t differentiate variable’s declaration in a one line. However, you could split it into two lines and use a different variable declaration, depends on which variable you want to get. const { a } = foo; let { b } = foo;
Updated: 16 February 2022 New Solution from Reselect 4.1: See detail // selector.js const selectItemsByCategory = createSelector( [ // Usual first input – extract value from `state` state => state.items, // Take the second arg, `category`, and forward to the output selector (state, category) => category ], // Output selector gets (`items, category)` as args … Read more