ECMAScript Expression Language is a web development scripting language that offers a concise and robust syntax for embedding dynamic expressions in web pages, applications and user interfaces. It is a powerful tool for developers to create interactive and dynamic platforms, with features such as filtering, binding, and formatting.
An introductory example of Esel is the expression, "The sum of 2 and 2 is ${2 + 2}." The whole string is an expression whose value is "The sum of 2 and 2 is 4." This example demonstrates the ease and simplicity of the Esel language. Any string is valid Esel expression, whose value is the same as the string itself. However, if there is text enclosed by "${" and "}", it gets replaced by the value of the expression between the two delimiters.
Although Esel was primarily created for the JSONForms web interface toolkit, it can have many other uses as well. It functions as an in-browser expression language which enables user-defined programs for rich web applications. Generally, user-defined programs are plain JavaScript or domain-specific languages, but using JavaScript creates a myriad of problems that Esel eliminates. Unlike JavaScript, Esel disallows assignment, so variables do not get clobbered. It strictly limits the accessible namespace and available functions to those explicitly exported by the application, thus ensuring that only valid expressions are used.
Another use of Esel is that it functions as a simple templating language. Some web browsers do not support XSLT, and not all programmers want to use it. Therefore, Esel provides a simple templating language that can be used within a web page, on the web browser itself. Today, this functionality is widely employed by JSONForms.
All in all, Esel is an exceptional language that helps programmers to seamlessly code expressions in JavaScript. It ensures safety and flexibility, making it a game-changing tool.
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