


In JavaScript code, you can use the alert() function of the window object to display a piece of text to debug the program, or to alert the user of relevant information:
//Use window object's alert() function
window.alert("sample text");
This writing method can be simplified to using the alert() function directly:
//Simplified alert() usage
alert("sample text");
If you need to display text with line breaks, you can use n:
//Use n in alert()
alert("The first linenThe second line");
If you need to use tab characters, you can use t:
//Use t in alert()
alert("Alext50t34nBobt59t38");
Use of variables
In addition to displaying static strings, the alert() function can also accept variables and concatenate the variable values with other strings:
//Use variable in alert()
var word = "life";
alert("The magic word is: " word ". Don't panic.");
Unfortunately, although the alert() function can accept variables, it can only do this string concatenation operation; contrary to another debugging method console.log(), the alert() function does not Accepts the method of passing parameters to strings. Take the following code as an example:
//Try to use parameter in alert(), will fail
var name = "Bob";
var years = 42;
alert("%s is %d years old.", name, years);
If the alert() function accepts a string parameter, the expected output result will be "Bob is 42 years old."; but in fact the alert() function does not support this, so the final output result is "%s is %d years old."
Pop-up window style
Since the pop-up box used by the alert() function is a browser system object rather than a web page document object, you cannot define the style of the pop-up box by using HTML tags in the alert() function - the HTML tags will be left intact. Display dynamically. For the following code:
//Try to use HTML tags in alert(), will fail
alert("Test Text");
The output result is not the bold "Test Text".
If you really need to change the style of the warning box, you have the following two options:
1. Use Unicode characters in the alert() function. The advantage of this solution is that it is very simple to implement, but its limitations are also obvious: the expressive power of Unicode characters is very limited.
2. Instead of using the alert() function, use HTML components to simulate pop-up boxes (such as using jQuery UI Dialog). The advantage of this solution is that the pop-up box will be very expressive, but its use will increase the complexity of the front-end code.
Conclusion
The alert() function can be used to alert users with information and can also be used to debug programs. For the former, using components such as jQuery UI Dialog can greatly increase expressiveness and user experience; for the latter, since the alert() pop-up box will block the execution of JavaScript code, in many cases, console.log() is used to Debugging the program is a better solution.

去掉重复并排序的方法:1、使用“Array.from(new Set(arr))”或者“[…new Set(arr)]”语句,去掉数组中的重复元素,返回去重后的新数组;2、利用sort()对去重数组进行排序,语法“去重数组.sort()”。

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怎么制作文字轮播与图片轮播?大家第一想到的是不是利用js,其实利用纯CSS也能实现文字轮播与图片轮播,下面来看看实现方法,希望对大家有所帮助!

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方法:1、利用“点击元素对象.unbind("click");”方法,该方法可以移除被选元素的事件处理程序;2、利用“点击元素对象.off("click");”方法,该方法可以移除通过on()方法添加的事件处理程序。

本篇文章给大家带来了关于JavaScript的相关知识,其中主要介绍了关于BOM操作的相关问题,包括了window对象的常见事件、JavaScript执行机制等等相关内容,下面一起来看一下,希望对大家有帮助。

foreach不是es6的方法。foreach是es3中一个遍历数组的方法,可以调用数组的每个元素,并将元素传给回调函数进行处理,语法“array.forEach(function(当前元素,索引,数组){...})”;该方法不处理空数组。


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