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I saw this snippet here:
render: function(): any {
var thread = this.state.thread;
var name = thread ? thread.name : "";
var messageListItems = this.state.messages.map(getMessageListItem);
return (
<div className="message-section">
<h3 className="message-thread-heading">{name}</h3>
// ...
What does the function(): any{ part in the first line mean?
Apologies if this has been asked before, but it's really hard to search this, particularly when you don't know what it's called.
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Points to Remember : JavaScript a function allows you to define a block of code, give it a name and then execute it as many times as you want. A function can be defined using function keyword and can be executed using () operator.
of() The Array. of() method creates a new Array instance from a variable number of arguments, regardless of number or type of the arguments. The difference between Array. of() and the Array constructor is in the handling of integer arguments: Array.
The jQuery syntax is tailor-made for selecting HTML elements and performing some action on the element(s). Basic syntax is: $(selector).action()
A function is simply a “chunk” of code that you can use over and over again, rather than writing it out multiple times. Functions enable programmers to break down or decompose a problem into smaller chunks, each of which performs a particular task.
That's not a part of JavaScript, it's an extra feature added by Flow, a JavaScript preprocessor. TypeScript also has a similar feature.
Essentially, Flow adds a type-checking feature, and to use it you add type-hinting to symbols. In this case, : any is a type hint for the render method, meaning the method could return any type.
any:
anyis a special type annotation that represents the universal dynamic type.anycan flow to any other type, and vice-versa.anyis basically the "get out of my way, I know what I am doing" annotation. Use it when Flow is getting in your way, but you know your program is correct.
A fun little side note, there was a proposed feature in the now-abandoned ES4 draft for type hinting that was very similar to this. As far as I know, it was only ever implemented in the ES-derived ActionScript 3.
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