A Review of ES6 - Extended Literals, Enhanced Regular Expression

Extended Literals

Binary & Octal Literal

Direct support for safe binary and octal literals

0b111110111 === 503
0o767 === 503

Unicode String & RegExp Literal

Extended support using Unicode within strings and regular expressions.

"𠮷".length === 2
"𠮷".match(/./u)[0].length === 2
"𠮷" === "\uD842\uDFB7"
"𠮷" === "\u{20BB7}"
"𠮷".codePointAt(0) == 0x20BB7
for (let codepoint of "𠮷") console.log(codepoint)

Enhanced Regular Expression

Regular Expression Sticky Matching

Keep the matching position sticky between matches and this way support efficient parsing of arbitrary long input strings, even with an arbitrary number of distinct regular expression.

let parser = (input, match) => {
    for (let pos = 0, lastPos = input.length; pos < lastPos; ) {
        for (let i = 0; i < match.length; i++) {
            match[i].pattern.lastIndex = pos
            let found
            if ((found = match[i].pattern.exec(input)) !== null) {
                match[i].action(found)
                pos = match[i].pattern.lastIndex
                break
            }
        }
    }
}

let report = (match) => {
    console.log(JSON.stringify(match))
}
parser("Foo 1 Bar 7 Baz 42", [
    { pattern: /Foo\s+(\d+)/y, action: (match) => report(match) },
    { pattern: /Bar\s+(\d+)/y, action: (match) => report(match) },
    { pattern: /Baz\s+(\d+)/y, action: (match) => report(match) },
    { pattern: /\s*/y,         action: (match) => {}            }
])

References: