In this article we want to learn How to debug JavaScript code, Debugging is crucial part of software development and it is no different when working with JavaScript. whether you are beginner or an experienced developer, there will come time when you need to debug your JavaScript code. In this article we are going to explore some of the ways you can debug JavaScript code.
Console.log() : One of the most straightforward ways to debug JavaScript code is to use console.log() function. It allows you to print messages or values to the browser console which you can then use to see the output of your code at specific points. for example:
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console.log('Hello, world!'); |
This will print the message “Hello, world!” to the console.
Breakpoints : Another way to debug JavaScript code is to use breakpoints. Breakpoints allow you to pause execution of your code at specific lines and examine the state of your variables and objects. you can set breakpoints in the browser developer tools or in your code using the debugger statement.
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function foo() { let x = 5; debugger; console.log(x); } foo(); |
In this example we have set breakpoint on debugger statement which will pause the execution of the code when it is reached. after that you can use developer tools to examine the value of the variable x.
Step Through Code : Once you have paused the execution of your code using breakpoint, you can step through your code one line at a time. this can help you identify where your code is going wrong and how to fix it. in the browser developer tools you can use step into, step over, and step out buttons to control the execution of your code.
Watch Expressions : Watch expressions allow you to monitor value of variable or expression as you step through your code. in the browser developer tools you can add watch expression by clicking on the add watch button and entering the name of the variable or expression you want to monitor.
Debugging JavaScript Errors : JavaScript errors can be frustrating to debug, but there are several techniques you can use to make the process easier. the first step is to identify type of the error you are dealing with, whether it is syntax error, runtime error or logic error. once you have identified the error, you can use console.log(), breakpoints and step through your code to find the source of the problem.