How to write javascript in url address bar

With the continuous development of front-end technology, we have been able to achieve a large number of dynamic effects in the browser. And JavaScript is one of the core technologies. Normally, we use this language by introducing external JavaScript files into html files. However, in some cases, we can also write JavaScript code directly in the URL address bar to achieve some specific functions. Next, let’s discuss how to write JavaScript code in the url address bar.

First, we need to understand some basic knowledge. By entering javascript: in the url address bar, you can tell the browser that the content we want to enter next is JavaScript code. For example, we can enter javascript:alert('Hello, World!') in the address bar, and a dialog box will pop up showing the message "Hello, World!".

In JavaScript code, we can use most of the language features. For example, we can define variables, call functions, use loops and conditional statements, and more. Below, we will introduce how to use JavaScript in the url address bar through several examples.

1. Highlight specific elements in the page
   Sometimes, we want to highlight a certain element in the page to attract the user's attention. At this time, we can enter the following JavaScript code in the url address bar:

javascript:document.getElementById("target_element_id").style.backgroundColor = "red";

Among them, target_element_id is the id of the element we want to highlight. With this code, we can set the background color of the element to red to achieve a highlighting effect.

2. Add new elements to the page
   Sometimes, we want to add new elements to the page to achieve some dynamic effects. At this time, we can achieve this by entering JavaScript code in the url address bar. For example, we can enter the following code in the address bar:

javascript:document.body.innerHTML += '<div>new element</div>';

This code implements the function of adding a new div element to the page. In fact, we can use any HTML code to achieve the effect of dynamically adding elements.

3. Display specific content on the page
   Sometimes, we want to quickly locate a keyword or specific content on the page. At this time, we can achieve this by entering JavaScript code in the url address bar. For example, we can enter the following code in the address bar:

javascript:window.find('keyword');

This code can find content with the keyword "keyword" on the page and locate the location of the content.

In short, using JavaScript in the url address bar can bring us a lot of convenience. However, it should be noted that entering JavaScript code into the page has certain risks. If there are security holes in the code we enter, it will bring great risks to our computers. Therefore, be sure to ensure the security of your code when using this technique.

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