What are the keywords of javascript-Front-end Q&A-php.cn

JavaScript is a programming language that is widely used in both front-end and back-end development. However, in JavaScript code, there are some words that are reserved keywords. These keywords have special meanings and functions and cannot be used as identifiers such as variable names or function names.

First of all, we need to understand what keywords are. Keywords refer to words or symbols that have been specified by a programming language as having a fixed meaning. For example, if, for, while, etc. in JavaScript are all keywords. These keywords play an important role in the syntax parsing and compilation process.

In JavaScript, the following is a list of reserved keywords:

break
case
catch
const
continue
debugger
default
delete
do
else
export
extends
finally
for
function
if
import
in
instanceof
new
return
super
switch
this
throw
try
typeof
var
void
while
with
yield

These reserved keywords have special meanings and cannot be used to define identifiers such as variables, functions, and object properties. If these keywords are used as identifiers, syntax errors will occur and the code will not run properly.

Let’s take a look at an example of a syntax error that occurs when using reserved keywords:

var function = "hello"; // 出现语法错误，不能用function作为变量名

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So, how to avoid using reserved keywords? Other identifiers can be used to name variables, functions, etc. In general, it is recommended to use descriptive words or phrases to better understand the code.

In addition to reserved keywords, there are some special global properties and methods in JavaScript that you also need to pay attention to. For example, the global object window, global variable undefined, global function eval, etc. need to pay attention to their special properties when using them.

In general, reserved keywords are an important part of JavaScript syntax and have mandatory restrictions. Careful inspection is required before use to avoid errors. At the same time, you also need to master the functions and meanings of keywords in order to better understand and write complex JavaScript programs.

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