JavaScript - Related Languages and Features - JavaScript and Java

JavaScript and Java

A common misconception is that JavaScript is similar or closely related to Java. It is true that both have a C-like syntax, the C language being their most immediate common ancestor language. They are both object-oriented, typically sandboxed (when used inside a browser), and are widely used in client-side Web applications. In addition, JavaScript was designed with Java's syntax and standard library in mind. In particular, all Java keywords were reserved in original JavaScript, JavaScript's standard library follows Java's naming conventions, and JavaScript's Math and Date objects are based on classes from Java 1.0.

JS had to "look like Java" only less so, be Java's dumb kid brother or boy-hostage sidekick. Plus, I had to be done in ten days or something worse than JS would have happened —Brendan Eich

However, the similarities end there. Java has static typing; JavaScript's typing is dynamic (meaning a variable can hold an object of any type and cannot be restricted). JavaScript is weakly typed ('0.0000' == 0, 0 == "", false == "", etc.) while Java is more strongly typed. Java is loaded from compiled bytecode; JavaScript is loaded as human-readable source code. Java's objects are class-based; JavaScript's are prototype-based. JavaScript also has many functional programming features based on the Scheme language.

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