Description
Overview
Everyone loves LATEX so ESNext will likely allow tagged template strings to contain backslashes on any sequence - even ones that look like they might contain an invalid Unicode escapes.
In other words, something like
let x = tag `\u{wat}`;is now valid, whereas previously it would be considered an error.
Reference: https://tc39.github.io/proposal-template-literal-revision/
As of this writing, the linked proposal is at Stage 3.
Notes
-
This restriction lift doesn't apply to untagged template strings. For example:
// All of these are still invalid. let bad = `bad escape sequence: \unicode`; let bracingOurselves = `\u{shouldntDoThis}`; let theWorst = `\xtremely bad`;
-
Because there is no appropriate representation for a "cooked" string that contains one of these escapes, the returned value at a position on the top-level array will be
undefined, but the raw representation will be available. For example:function tag(strs) { console.log(strs[0] === undefined); console.log(strs.raw[0] === "\\unicode and \\u{55}"); }
// Prints 'true' twice.
tag\unicode and \u{55}
Proposed Emit
Input:
let x = tag `\u{hello} ${ 100 } \xtraordinary ${ 200 } wonderful ${ 300 } \uworld`;Output:
var x = (
_a = [undefined, undefined, " wonderful ", undefined],
_a.raw = ["\\u{hello} ", " \\xtraordinary ", " wonderful ", " \\uworld"],
tag(_a, 100, 200, 300)
);