我想在JavaScript中创建String.replaceAll（）方法，我认为使用正则表达式是最简洁的方法。然而，我无法确定如何将变量传递给正则表达式。我已经可以这样做了，这将用“A”替换“B”的所有实例。
"ABABAB".replace(/B/g, "A");
但我想这样做：
String.prototype.replaceAll = function(replaceThis, withThis) {
this.replace(/replaceThis/g, withThis);
};
但显然，这只会替换文本“replaceThis”。。。那么如何将此变量传递到正则表达式字符串中？
当前回答
您始终可以重复使用indexOf：
String.prototype.replaceAll = function(substring, replacement) {
var result = '';
var lastIndex = 0;
while(true) {
var index = this.indexOf(substring, lastIndex);
if(index === -1) break;
result += this.substring(lastIndex, index) + replacement;
lastIndex = index + substring.length;
}
return result + this.substring(lastIndex);
};
当替换包含匹配项时，这不会进入无限循环。
其他回答
this.replace( new RegExp( replaceThis, 'g' ), withThis );
我在这里和stackoverflow或类似论坛上的其他公开门票中找到了很多带有奇怪例子的答案。
这是我认为最简单的选项，如何将变量作为模板文本字符串；
const someString = "abc";
const regex = new RegExp(`^ someregex ${someString} someregex $`);
正如您所看到的，我没有在开头或结尾处使用正斜杠，RegExp构造函数将重建有效的正则表达式文字。还可以使用yup matches函数。
为了满足我在正则表达式中插入变量/别名/函数的需要，我想到了以下方法：
oldre = /xx\(""\)/;
function newre(e){
return RegExp(e.toString().replace(/\//g,"").replace(/xx/g, yy), "g")
};
String.prototype.replaceAll = this.replace(newre(oldre), "withThis");
其中“oldre”是我要插入变量的原始正则表达式，“xx”是该变量/别名/函数的占位符，“yy”是实际变量名、别名或函数。
作为一个相对的JavaScript新手，公认的答案https://stackoverflow.com/a/494046/1904943值得注意/赞赏，但这不是很直观。
这里有一个更简单的解释，例如（使用一个简单的JavaScript IDE）。
myString = 'apple pie, banana loaf';
console.log(myString.replaceAll(/pie/gi, 'PIE'))
// apple PIE, banana loaf
console.log(myString.replaceAll(/\bpie\b/gi, 'PIE'))
// apple PIE, banana loaf
console.log(myString.replaceAll(/pi/gi, 'PIE'))
// apple PIEe, banana loaf
console.log(myString.replaceAll(/\bpi\b/gi, 'PIE'))
// [NO EFFECT] apple pie, banana loaf
const match_word = 'pie';
console.log(myString.replaceAll(/match_word/gi, '**PIE**'))
// [NO EFFECT] apple pie, banana loaf
console.log(myString.replaceAll(/\b`${bmatch_word}`\b/gi, '**PIE**'))
// [NO EFFECT] apple pie, banana loaf
// ----------------------------------------
// ... new RegExp(): be sure to \-escape your backslashes: \b >> \\b ...
const match_term = 'pie';
const match_re = new RegExp(`(\\b${match_term}\\b)`, 'gi')
console.log(myString.replaceAll(match_re, 'PiE'))
// apple PiE, banana loaf
console.log(myString.replace(match_re, '**PIE**'))
// apple **PIE**, banana loaf
console.log(myString.replaceAll(match_re, '**PIE**'))
// apple **PIE**, banana loaf
应用
例如：替换字符串/句子中的单词（颜色突出显示），如果搜索词与匹配单词的用户定义比例相匹配，则[可选]。
注：匹配术语的原始字符大小写保留。hl：高光；re:regex |正则表达式
mySentence = "Apple, boOk? BOoks; booKEd. BookMark, 'BookmarkeD', bOOkmarks! bookmakinG, Banana; bE, BeEn, beFore."
function replacer(mySentence, hl_term, hl_re) {
console.log('mySentence [raw]:', mySentence)
console.log('hl_term:', hl_term, '| hl_term.length:', hl_term.length)
cutoff = hl_term.length;
console.log('cutoff:', cutoff)
// `.match()` conveniently collects multiple matched items
// (including partial matches) into an [array]
const hl_terms = mySentence.toLowerCase().match(hl_re, hl_term);
if (hl_terms == null) {
console.log('No matches to hl_term "' + hl_term + '"; echoing input string then exiting ...')
return mySentence;
}
console.log('hl_terms:', hl_terms)
for (let i = 0; i < hl_terms.length; i++) {
console.log('----------------------------------------')
console.log('[' + i + ']:', hl_terms[i], '| length:', hl_terms[i].length, '| parseInt(0.7(length)):', parseInt(0.7*hl_terms[i].length))
// TEST: if (hl_terms[i].length >= cutoff*10) {
if (cutoff >= parseInt(0.7 * hl_terms[i].length)) {
var match_term = hl_terms[i].toString();
console.log('matched term:', match_term, '[cutoff length:', cutoff, '| 0.7(matched term length):', parseInt(0.7 * hl_terms[i].length))
const match_re = new RegExp(`(\\b${match_term}\\b)`, 'gi')
mySentence = mySentence.replaceAll(match_re, '<font style="background:#ffe74e">$1</font>');
}
else {
var match_term = hl_terms[i].toString();
console.log('NO match:', match_term, '[cutoff length:', cutoff, '| 0.7(matched term length):', parseInt(0.7 * hl_terms[i].length))
}
}
return mySentence;
}
// TESTS:
// const hl_term = 'be';
// const hl_term = 'bee';
// const hl_term = 'before';
// const hl_term = 'book';
const hl_term = 'bookma';
// const hl_term = 'Leibniz';
// This regex matches from start of word:
const hl_re = new RegExp(`(\\b${hl_term}[A-z]*)\\b`, 'gi')
mySentence = replacer(mySentence, hl_term, hl_re);
console.log('mySentence [processed]:', mySentence)
输出
mySentence [raw]: Apple, boOk? BOoks; booKEd. BookMark, 'BookmarkeD',
bOOkmarks! bookmakinG, Banana; bE, BeEn, beFore.
hl_term: bookma | hl_term.length: 6
cutoff: 6
hl_terms: Array(4) [ "bookmark", "bookmarked", "bookmarks", "bookmaking" ]
----------------------------------------
[0]: bookmark | length: 8 | parseInt(0.7(length)): 5
matched term: bookmark [cutoff length: 6 | 0.7(matched term length): 5
----------------------------------------
[1]: bookmarked | length: 10 | parseInt(0.7(length)): 7
NO match: bookmarked [cutoff length: 6 | 0.7(matched term length): 7
----------------------------------------
[2]: bookmarks | length: 9 | parseInt(0.7(length)): 6
matched term: bookmarks [cutoff length: 6 | 0.7(matched term length): 6
----------------------------------------
[3]: bookmaking | length: 10 | parseInt(0.7(length)): 7
NO match: bookmaking [cutoff length: 6 | 0.7(matched term length): 7
mySentence [processed]: Apple, boOk? BOoks; booKEd.
<font style="background:#ffe74e">BookMark</font>, 'BookmarkeD',
<font style="background:#ffe74e">bOOkmarks</font>! bookmakinG,
Banana; bE, BeEn, beFore.
如果要获取所有出现的单词（g），请区分大小写（i），并使用边界，使其不是另一个单词中的单词（\\b）：
re = new RegExp(`\\b${replaceThis}\\b`, 'gi');
let inputString=“我是John或johnny，但我更喜欢John。”；let replaceThis=“John”；let re=新RegExp（`\\b$｛replaceThis｝\\b`，'gi'）；console.log（inputString.replace（re，“Jack”））；
