6 Source Text

ECMAScript source text is represented as a sequence of characters representable using the Unicode version 2.0 character encoding.

SourceCharacter ::

any Unicode character

Except within comments and string literals, every ECMAScript program shall consist of only characters from the first 128 Unicode characters (that is, the first half of row zero). Other Unicode characters may appear only within comments and string literals. In string literals, any Unicode character may also be expressed as a Unicode escape sequence consisting of six characters from the first 128 characters, namely \u plus four hexadecimal digits. Within a comment, such an escape sequence is effectively ignored as part of the comment. Within a string literal, the Unicode escape sequence contributes one character to the string value of the literal.

Although the characters in an ECMAScript program are Unicode characters, they are treated as independent 16-bit values with none of the context-dependent interpretation specified in the Unicode standard. Such values are often called "code points". The Unicode standard refers to code points as "coded character data elements". Throughout this International standard the terms "character" and "code point" are understood to mean "coded character data element".

NOTE ECMAScript differs from the Java programming language in the behaviour of Unicode escape sequences. In a Java program, if the Unicode escape sequence \u000A , for example, occurs within a single-line comment, it is interpreted as a line terminator (Unicode character 000A is line feed) and therefore the next character is not part of the

comment. Similarly, if the Unicode escape sequence \u000A occurs within a string literal in a Java program, it is likewise interpreted as a line terminator, which is not allowed within a string literal—one must write \n instead of \u000A to cause a line feed to be part of the string value of a string literal. In an ECMAScript program, a Unicode escape sequence occurring within a comment is never interpreted and therefore cannot contribute to termination of the comment. Similarly, a Unicode escape sequence occurring within a string literal in an ECMAScript program always contributes a character to the string value of the literal and is never interpreted as a line terminator or as a quote mark that might terminate the string literal.