javascript - javascript string.replace 是线性的吗？

Question

是 javascript 的 string.replace 线性替换还是有一些时髦的优化？基本上，我的问题是这段代码的结果是按数字顺序排列的吗？

  var index = 0;
  html = html.replace(/replaceIndex/g, function (match, capture) {
    return index++;
  });

我觉得这个问题的答案是“它取决于 x”，其中 x 是 firefox、chrome、v8、rhino 等。

Answer 1

ES5似乎没有指定调用顺序:

for each matched substring, call the function with the following m + 3 arguments.

但是，ES6 可以。 String.prototype.replace使用 RegExp.prototype[@@replace]哪个(恢复)表现得像

21.2.5.8 RegExp.prototype [ @@replace ] ( string, replaceValue )

• Let S be ToString(string).
• Let results be a new empty List.
• Repeat
  • Let result be RegExpExec(rx, S).
  • Append result to the end of results.
• Let accumulatedResult be the empty String value.
• Let nextSourcePosition be 0.
• Repeat, for each result in results,
  • Let position be ToInteger(Get(result, "index")).
  • Let position be max(min(position, lengthS), 0).
  • Let replValue be Call(replaceValue, undefined, replacerArgs).
  • Let replacement be ToString(replValue).
  • If position ≥ nextSourcePosition, then
    • NOTE position should not normally move backwards. If it does, it is an indication of an ill-behaving RegExp subclass or use of an access triggered side-effect to change the global flag or other characteristics of rx. In such cases, the corresponding substitution is ignored.
    • Let accumulatedResult be the String formed by concatenating the code units of the current value of accumulatedResult with the substring of S consisting of the code units from nextSourcePosition (inclusive) up to position (exclusive) and with the code units of replacement.
    • Let nextSourcePosition be position + matchLength.
• If nextSourcePosition ≥ lengthS, return accumulatedResult.
• Return the String formed by concatenating the code units of accumulatedResult with the substring of S consisting of the code units from nextSourcePosition (inclusive) up through the final code unit of S (inclusive).