如何在 JavaScript 字符串中按索引替换字符？
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How to replace characters by index in a JavaScript string?
提问by vcapra1
If I have the string "hello" and I want to replace the second and third character with _, how can i do that, given only the location of the substring, not what it actually is.
如果我有字符串“hello”并且我想用 _ 替换第二个和第三个字符，我该怎么做，只给出子字符串的位置，而不是它的实际位置。
回答by MikeM
str = str.replace( /^(.)../, '__' );
The .matches any character except a newline.
该.换行符以外的任何字符匹配。
The ^represents the start of the string.
该^表示字符串的开始。
The ()captures the character matched by the first .so it can be referenced in the replacement string by $1.
在()捕获的第一个匹配的字符.，因此它可以通过替换字符串中引用$1。
Anything that matches the regular expression is replaced by the replacement string '$1__', so the first three characters at the start of the string are matched and replaced with whatever was matched by the first .plus __.
与正则表达式匹配的任何内容都将被替换字符串替换'$1__'，因此字符串开头的前三个字符将被匹配并替换为与第一个.加号匹配的任何内容__。
回答by jn_pdx
String.prototype.replaceAt=function(index, character) {
return this.substr(0, index) + character + this.substr(index+character.length);
}
str.replaceAt(1,"_");
str.replaceAt(2,"_");
Taken from: How do I replace a character at a particular index in JavaScript?
