Shulou(Shulou.com)06/02 Report--

This article mainly explains "what is the importance of JavaScript debugging". Interested friends may wish to have a look at it. The method introduced in this paper is simple, fast and practical. Let's let the editor take you to learn "what is the importance of JavaScript debugging"?

When writing JavaScript, it can be painful without a debugging tool.

It is difficult to write JavaScript programs without debugging tools. Your code may contain syntax errors, logic errors, which can be difficult to find without debugging tools.

Usually, if there is an error in JavaScript, there will be no prompt, so you can't find the location of the code error.

Looking for errors in program code is called "code debugging".

Debugging is difficult, but fortunately, many browsers have built-in debugging tools.

Built-in debugging tools can be turned on or off, and serious error messages are sent to the user.

With debugging tools, we can set breakpoints (where the code stops executing) and detect variables as the code executes.

The browser generally enables debugging tools by pressing the F12 key and selecting "Console" from the debugging menu.

Console.log () method:

If the browser supports debugging, you can use the console.log () method to print the JavaScript value on the debug window:

Set the breakpoint:

In the debug window, you can set a breakpoint for your JavaScript code.

At each breakpoint, the execution of the JavaScript code is stopped so that we can check the value of the JavaScript variable.

After the check, you can re-execute the code (such as the play button).

Debugger keyword:

The debugger keyword is used to stop the execution of the JavaScript and call the debug function.

This keyword has the same effect as setting a breakpoint in the debugger.

If debugging is not available, debugger statements will not work.

JavaScript variable promotion (hoisting):

In JavaScript, the declaration of functions and variables will be promoted to the top of the function. Function and variable declarations are always quietly "promoted" to the top of the method body by the interpreter.

In JavaScript, variables can be declared after use, that is, variables can be used before declaration.

Only declared variables in JavaScript will be promoted, not initialized ones.

Declare your variables in the header

JavaScript variable promotion is not known to most programmers.

If programmers do not understand variable promotion well, the programs they write are prone to some problems.

To avoid these problems, we usually declare these variables before each scope starts, which is also a normal JavaScript parsing step that is easy for us to understand.

At this point, I believe you have a deeper understanding of "what is the importance of JavaScript debugging". You might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.