In JavaScript, you can perform global error handling on the page by binding the "window.onerrot" event. The syntax format is "function function name (msg, url, l, c, error) {//code} window.onerror = function name;".
The operating environment of this tutorial: windows7 system, javascript version 1.8.5, Dell G3 computer.
When the JavaScript engine executes JavaScript code, various errors will occur: it may be grammatical or spelling errors, it may be browser differences (browser-specific functions are used), or the server may return an unhandled exception. Of course There are many other unpredictable factors. When an error occurs, the JavaScript engine interrupts subsequent code execution and generates an error message. In order to make the code more robust and avoid unexpected code interruptions, we need to handle various exceptions.
1. Local error handling
Local error handling refers to error capture and processing where the code may go wrong, which requires programmers to perform hard coding. There are 4 JavaScript error handling related Statements:
1) try, catch statement, error capture statement
2) final statement, after error capture processing, return pre-execution statement
3) throw statement , error throw statement
Case 1:
try {
window.abcdefg();
} catch (e) {
alert('发生错误啦，错误信息为：' e.message);
} finally {//总是会被执行
alert('我都会执行！');
}Console output:
An error occurred, the error message is: window. abcdefg is not a function
I will execute the
finally statement after catch and before return.
Case 2
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Throw Demo</title>
</head>
<body>
<script>
function myFunction()
{
try
{
var x=document.getElementById("demo").value;
if(x=="") throw "不能为空";
if(isNaN(x)) throw "不是有效数字";
if(x>10) throw "不能大于10";
if(x<5) throw "不能小于5";
} catch(err) {
var y=document.getElementById("mess");
y.innerHTML="Error: " + err + ".";
}
}
</script>
<p>请输入一个5到10的数字：</p>
<input id="demo" type="text">
<button type="button" onclick="myFunction()">Test Input</button>
<p id="mess"></p>
</body>
</html>The function of throw is to escape foreseeable or unforeseeable errors into user-recognizable errors.
[Recommended learning: javascript advanced tutorial]
2. Global error handling
Due to the different levels of front-end developers , The degree of code standardization varies, and not all JavaScript codes have error handling. Therefore, JavaScript code often terminates unexpectedly due to unforeseen exceptions during execution. For this reason, we need to globally capture error exceptions and promptly remind developers to modify the code. As long as the window.onerrot event is bound, the global js error error handling on the page can be performed. The code is as follows:
function globalErrorHandle(msg,url,l,c,error) {
console.error("global js error: ", msg, l);
// TODO other things.
}
window.onerror = globalErrorHandle;Bind the window.onerrot event, and the globalErrorHandle will be called when the js error is reported, where:
msg: Error message
url: Error page url
- ##l: Code error line number c: Column number
- error: Error object
Console output: 
3. Error reporting module design
Global error handling cannot The blocking code terminates unexpectedly, which means that when an error is reported during js execution and there is no try-catch error handling, globalErrorHandle will be called, but the subsequent code will terminate unexpectedly and will not be executed. Therefore, global error handling is more about global error recording and reporting. Usually three things are done:- globalErrorHandle, global error capture; report error information to the server (error page, line number, column number, etc.) ;
- When the administrator discovers the js error message on the server, he orders the relevant personnel to modify it;
The picture above is a simple js error reporting module, error viewing page, information includes: error source (which page), error description, line number, operating system browser, operator, operation time, etc.
There are several things to note:
1) Filtering of reported content
As shown in the picture above shows that many error messages are the same. If errors are continuously triggered in a large loop, error messages will continue to be sent to the server. Therefore, filter the error messages before sending them. The operation is as follows:- When the page is loaded, first obtain the error source error description hashcode deduplication list;
- When capturing global errors, whether the generated error source error description hashcode already exists, if not, an error message will be reported;
2) What content to report
In order to reproduce the error, it is recommended to make the error message as detailed as possible, at least including:- Error Page url
- Error description, error line number, column number, stack information
- Browser and operating system information
- Operation time, even operator, parameters
Programming Video! !
The above is the detailed content of How to handle global errors in javascript. For more information, please follow other related articles on the PHP Chinese website!
JavaScript in Action: Real-World Examples and ProjectsApr 19, 2025 am 12:13 AMJavaScript's application in the real world includes front-end and back-end development. 1) Display front-end applications by building a TODO list application, involving DOM operations and event processing. 2) Build RESTfulAPI through Node.js and Express to demonstrate back-end applications.
JavaScript and the Web: Core Functionality and Use CasesApr 18, 2025 am 12:19 AMThe main uses of JavaScript in web development include client interaction, form verification and asynchronous communication. 1) Dynamic content update and user interaction through DOM operations; 2) Client verification is carried out before the user submits data to improve the user experience; 3) Refreshless communication with the server is achieved through AJAX technology.
Understanding the JavaScript Engine: Implementation DetailsApr 17, 2025 am 12:05 AMUnderstanding how JavaScript engine works internally is important to developers because it helps write more efficient code and understand performance bottlenecks and optimization strategies. 1) The engine's workflow includes three stages: parsing, compiling and execution; 2) During the execution process, the engine will perform dynamic optimization, such as inline cache and hidden classes; 3) Best practices include avoiding global variables, optimizing loops, using const and lets, and avoiding excessive use of closures.
Python vs. JavaScript: The Learning Curve and Ease of UseApr 16, 2025 am 12:12 AMPython is more suitable for beginners, with a smooth learning curve and concise syntax; JavaScript is suitable for front-end development, with a steep learning curve and flexible syntax. 1. Python syntax is intuitive and suitable for data science and back-end development. 2. JavaScript is flexible and widely used in front-end and server-side programming.
Python vs. JavaScript: Community, Libraries, and ResourcesApr 15, 2025 am 12:16 AMPython and JavaScript have their own advantages and disadvantages in terms of community, libraries and resources. 1) The Python community is friendly and suitable for beginners, but the front-end development resources are not as rich as JavaScript. 2) Python is powerful in data science and machine learning libraries, while JavaScript is better in front-end development libraries and frameworks. 3) Both have rich learning resources, but Python is suitable for starting with official documents, while JavaScript is better with MDNWebDocs. The choice should be based on project needs and personal interests.
From C/C to JavaScript: How It All WorksApr 14, 2025 am 12:05 AMThe shift from C/C to JavaScript requires adapting to dynamic typing, garbage collection and asynchronous programming. 1) C/C is a statically typed language that requires manual memory management, while JavaScript is dynamically typed and garbage collection is automatically processed. 2) C/C needs to be compiled into machine code, while JavaScript is an interpreted language. 3) JavaScript introduces concepts such as closures, prototype chains and Promise, which enhances flexibility and asynchronous programming capabilities.
JavaScript Engines: Comparing ImplementationsApr 13, 2025 am 12:05 AMDifferent JavaScript engines have different effects when parsing and executing JavaScript code, because the implementation principles and optimization strategies of each engine differ. 1. Lexical analysis: convert source code into lexical unit. 2. Grammar analysis: Generate an abstract syntax tree. 3. Optimization and compilation: Generate machine code through the JIT compiler. 4. Execute: Run the machine code. V8 engine optimizes through instant compilation and hidden class, SpiderMonkey uses a type inference system, resulting in different performance performance on the same code.
Beyond the Browser: JavaScript in the Real WorldApr 12, 2025 am 12:06 AMJavaScript's applications in the real world include server-side programming, mobile application development and Internet of Things control: 1. Server-side programming is realized through Node.js, suitable for high concurrent request processing. 2. Mobile application development is carried out through ReactNative and supports cross-platform deployment. 3. Used for IoT device control through Johnny-Five library, suitable for hardware interaction.
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
mPDF
mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),
SecLists
SecLists is the ultimate security tester's companion. It is a collection of various types of lists that are frequently used during security assessments, all in one place. SecLists helps make security testing more efficient and productive by conveniently providing all the lists a security tester might need. List types include usernames, passwords, URLs, fuzzing payloads, sensitive data patterns, web shells, and more. The tester can simply pull this repository onto a new test machine and he will have access to every type of list he needs.
WebStorm Mac version
Useful JavaScript development tools
DVWA
Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software
Zend Studio 13.0.1
Powerful PHP integrated development environment
