JavaScript
JavaScript has a single number type. Internally, it is represented as 64-bit floating point, the same as Java’s double
Unlike most other programming languages, there is no separate integer type, so 1 and 1.0 are the same value.
A string literal can be wrapped in single quotes or double quotes. It can contain zero or more characters. The (backslash) is the escape character. JavaScript was built at a time when Unicode was a 16-bit character set, so all characters in JavaScript are 16 bits wide.
JavaScript does not have a character type. To represent a character, make a string with just one character in it.
Strings have a length property. For example, “seven”.length is 5.
Strings are immutable. Once it is made, a string can never be changed.
it is easy to make a new string by concatenating other strings together with the + operator.
Two strings containing exactly the same characters in the same order are considered to be the same string. So: ‘c’ + ‘a’ + ‘t’ === ‘cat’ is true.
A compilation unit contains a set of executable statements. In web browsers, each