I have a problem with one of the requests that the project asks. It is number 4. It asks for:
Each element with the class of “main-section” should also have an id comprised of the innerText contained within it, with underscores in place of spaces. The id may include special characters if there are special characters in the respective innerText. (e.g. The that contains the header, “JavaScript & Java”, should have a corresponding id=“JavaScript_&_Java”). I do what it asks but it doesn’t accept it. Is it something wrong with my code or it’s just codepen’s fault?
<section class="main-section" id="Introduction"><header>Introduction</header><P>JavaScript is a cross-platform, object-oriented scripting language. It is a small and lightweight language. Inside a host environment (for example, a web browser), JavaScript can be connected to the objects of its environment to provide programmatic control over them.</P>
<P>JavaScript contains a standard library of objects, such as Array, Date, and Math, and a core set of language elements such as operators, control structures, and statements. Core JavaScript can be extended for a variety of purposes by supplementing it with additional objects; for example:</P>
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<section class="main-section" id="What_you_should_already_know"><header>What you should already know</header>
<P>This guide assumes you have the following basic background</P>
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<section class="main-section" id="JavaScript_and_Java"><header>JavaScript and Java</header> <P>JavaScript and Java are similar in some ways but fundamentally different in some others. The JavaScript language resembles Java but does not have Java's static typing and strong type checking. JavaScript follows most Java expression syntax, naming conventions and basic control-flow constructs which was the reason why it was renamed from LiveScript to JavaScript.</P>
<P>In contrast to Java's compile-time system of classes built by declarations, JavaScript supports a runtime system based on a small number of data types representing numeric, Boolean, and string values. JavaScript has a prototype-based object model instead of the more common class-based object model. The prototype-based model provides dynamic inheritance; that is, what is inherited can vary for individual objects. JavaScript also supports functions without any special declarative requirements. Functions can be properties of objects, executing as loosely typed methods.</P>
<P>JavaScript is a very free-form language compared to Java. You do not have to declare all variables, classes, and methods. You do not have to be concerned with whether methods are public, private, or protected, and you do not have to implement interfaces. Variables, parameters, and function return types are not explicitly typed.</P>
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<header>Hello world</header> <P>To get started with writing JavaScript, open the Scratchpad and write your first "Hello world" JavaScript code:</P></section>
<section class="main-section" id="Variables"><header>Variables</header> <P>You use variables as symbolic names for values in your application. The names of variables, called identifiers, conform to certain rules.</P>
<P>A JavaScript identifier must start with a letter, underscore (_), or dollar sign ($); subsequent characters can also be digits (0-9). Because JavaScript is case sensitive, letters include the characters "A" through "Z" (uppercase) and the characters "a" through "z" (lowercase).</P> <P>You can use ISO 8859-1 or Unicode letters such as å and ü in identifiers. You can also use the Unicode escape sequences as characters in identifiers. Some examples of legal names are Number_hits, temp99, and _name.</P>
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<section class="main-section" id="Declaring_variables"><header>Declaring variables</header></section>