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How to debug code when js encounters code problems
- angryTomforward
- 2020-02-05 17:54:192142browse
This article introduces the debugging method if you encounter problems when writing JavaScript code. I hope it will be helpful to all students learning JavaScript!
How to debug code when js encounters code problems
Single-step tracking debugging debugger;
The console watch function checks the current value of the variable
Enters the function operation
As it continues Click to continue looping, and the value of the specified variable is also changing
Add a breakpoint
Jump in Jump out of the function
throw new Error() actively throws an exception
The following code will no longer run
The code will jump Go to the try statement closest to this sentence
Use
try{
}catch(e){
}Receive exception
##
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Document</title>
</head>
<body>
<script>
try{
var foo={};
console.log(foo.pro);
}catch(e){
console.log(e);//undefined
}finally{
console.log('异常导致程序中止啦~');//异常导致程序中止啦~
}
</script>
</body>
</html>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Document</title>
</head>
<body>
<script>
function multi(num1, num2){
if(typeof num1 != "number" || typeof num2 != "number"){
throw new Error('必须输入数字!!!');
}
console.log(num1*num2);
}
try{
//multi("a", "b");//Error: 必须输入数字!!!
multi(1, 2);//2
}catch(e){
console.log(e);
}finally{
console.log('不管有没有异常我都要执行哈~');
}
</script>
</body>
</html> This article comes from the js tutorial column, welcome to learn!
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