From 64da7ff0d44524335d1b589afd59e4874068def7 Mon Sep 17 00:00:00 2001 From: Ilya Kantor Date: Sun, 12 Dec 2021 22:26:59 +0300 Subject: [PATCH] minor fixes --- .../16-function-expressions/article.md | 28 +++++++++++++------ 1 file changed, 20 insertions(+), 8 deletions(-) diff --git a/1-js/02-first-steps/16-function-expressions/article.md b/1-js/02-first-steps/16-function-expressions/article.md index a8ccd6c6..f6ae9291 100644 --- a/1-js/02-first-steps/16-function-expressions/article.md +++ b/1-js/02-first-steps/16-function-expressions/article.md @@ -12,7 +12,9 @@ function sayHi() { There is another syntax for creating a function that is called a *Function Expression*. -It looks like this: +It allows to create a new function in the middle of any expression. + +For example: ```js let sayHi = function() { @@ -20,9 +22,19 @@ let sayHi = function() { }; ``` -Here, the function is created and assigned to the variable explicitly, like any other value. No matter how the function is defined, it's just a value stored in the variable `sayHi`. +Here we can see a variable `sayHi` getting a value, the new function, created as `function() { alert("Hello"); }`. -The meaning of these code samples is the same: "create a function and put it into the variable `sayHi`". +As the function creation happens in the context of the assignment expression (to the right side of `=`), this is a *Function Expression*. + +Please note, there's no name after the `function` keyword. Omitting a name is allowed for Function Expressions. + +Here we immediately assign it to the variable, so the meaning of these code samples is the same: "create a function and put it into the variable `sayHi`". + +In more advanced situations, that we'll come across later, a function may be created and immediately called or scheduled for a later execution, not stored anywhere, thus remaining anonymous. + +## Function is a value + +Let's reiterate: no matter how the function is created, a function is a value. Both examples above store a function is `sayHi` variable. We can even print out that value using `alert`: @@ -63,10 +75,10 @@ Here's what happens above in detail: 2. Line `(2)` copies it into the variable `func`. Please note again: there are no parentheses after `sayHi`. If there were, then `func = sayHi()` would write *the result of the call* `sayHi()` into `func`, not *the function* `sayHi` itself. 3. Now the function can be called as both `sayHi()` and `func()`. -Note that we could also have used a Function Expression to declare `sayHi`, in the first line: +We could also have used a Function Expression to declare `sayHi`, in the first line: ```js -let sayHi = function() { +let sayHi = function() { // (1) create alert( "Hello" ); }; @@ -90,9 +102,9 @@ let sayHi = function() { }*!*;*/!* ``` -The answer is simple: -- There's no need for `;` at the end of code blocks and syntax structures that use them like `if { ... }`, `for { }`, `function f { }` etc. -- A Function Expression is used inside the statement: `let sayHi = ...;`, as a value. It's not a code block, but rather an assignment. The semicolon `;` is recommended at the end of statements, no matter what the value is. So the semicolon here is not related to the Function Expression itself, it just terminates the statement. +The answer is simple: a Function Expression is created here as `function(…) {…}` inside the assignment statement: `let sayHi = …;`. The semicolon `;` is recommended at the end of the statement, it's not a part of the function syntax. + +The semicolon would be there for a simpler assignment, such as `let sayHi = 5;`, and it's also there for a function assignment. ```` ## Callback functions