The solution is the binding of variables through closure. As a more basic example, here is an example function that receives and calls a callback function, as well as an example callback function: function callbackReceiver(callback) { callback(“Hello World”); } function callback(value1, value2) { console.log(value1, value2); } This calls the callback and supplies a single argument. … Read more
subscribe isn’t deprecated, only the variant you’re using is deprecated. In the future, subscribe will only take one argument: either the next handler (a function) or an observer object. So in your case you should use: .subscribe({ next: this.handleUpdateResponse.bind(this), error: this.handleError.bind(this) }); See these GitHub issues: https://github.com/ReactiveX/rxjs/pull/4202 https://github.com/ReactiveX/rxjs/issues/4159
Please refer to update_attribute. On clicking show source you will get following code # File vendor/rails/activerecord/lib/active_record/base.rb, line 2614 2614: def update_attribute(name, value) 2615: send(name.to_s + ‘=’, value) 2616: save(false) 2617: end and now refer update_attributes and look at its code you get # File vendor/rails/activerecord/lib/active_record/base.rb, line 2621 2621: def update_attributes(attributes) 2622: self.attributes = attributes 2623: … Read more
Yes there is, since setState works in an asynchronous way. That means after calling setState the this.state variable is not immediately changed. so if you want to perform an action immediately after setting state on a state variable and then return a result, a callback will be useful Consider the example below …. changeTitle: function … Read more
Array.forEach does not provide this nicety (oh if it would) but there are several ways to accomplish what you want: Using a simple counter function callback () { console.log(‘all done’); } var itemsProcessed = 0; [1, 2, 3].forEach((item, index, array) => { asyncFunction(item, () => { itemsProcessed++; if(itemsProcessed === array.length) { callback(); } }); }); … Read more
The point seems to be that sometimes, you need a property that has automatic storage and some behavior, for instance to notify other objects that the property just changed. When all you have is get/set, you need another field to hold the value. With willSet and didSet, you can take action when the value is … Read more
EDIT: In summary, back in 2010 when this question was asked the most common way to solve this problem was to save a reference to the context where the setTimeout function call is made, because setTimeout executes the function with this pointing to the global object: var that = this; if (this.options.destroyOnHide) { setTimeout(function(){ that.tip.destroy() … Read more
The “good node.js /event driven” way of doing this is to not wait. Like almost everything else when working with event driven systems like node, your function should accept a callback parameter that will be invoked when then computation is complete. The caller should not wait for the value to be “returned” in the normal … Read more
Actually, your code will pretty much work as is, just declare your callback as an argument and you can call it directly using the argument name. The basics function doSomething(callback) { // … // Call the callback callback(‘stuff’, ‘goes’, ‘here’); } function foo(a, b, c) { // I’m the callback alert(a + ” ” + … Read more
If you want something slightly more general, you can use the arguments variable like so: function tryMe(param1, param2) { alert(param1 + ” and ” + param2); } function callbackTester(callback) { callback(arguments[1], arguments[2]); } callbackTester(tryMe, “hello”, “goodbye”); But otherwise, your example works fine (arguments[0] can be used in place of callback in the tester)