替换字符串的前N个出现次数
it1352
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问题说明
如何在以下字符串中替换第一个 N 出现的许多空格和制表符：
How can I replace first N occurrences of many whitespaces and tabs in the following string:
07/12/2017 11:01 AM 21523 filename with s p a c e s.js
我期待以下结果：
07/12/2017|11:01|AM|21523|filename with s p a c e s.js
我只知道通过调用replace N 相同字符串上的次数
I know not very elegant option only via calling replace N times on the same string
.replace(/\s /, "|").replace(/\s /, "|").replace(/\s /, "|");
值得一提的是，我将在近1,000,000行运行此项，因此性能至关重要。
Worth to mention that I'm going to run this on near 1,000,000 lines so performance matters.
正确答案
#1
你可以拿一个计数器并递减它。
You could take a counter and decrement it.
var string = '07/12/2017 11:01 AM 21523 filename with s p a c e s.js',
n = 4,
result = string.replace(/\s /g, s => n ? (n--, '|') : s);
console.log(result);你可以替换三元表达式一个具有逻辑AND和OR。
You could replace the ternary expression with one with logical AND and OR.
var string = '07/12/2017 11:01 AM 21523 filename with s p a c e s.js',
n = 4,
result = string.replace(/\s /g, s => n && n-- && '|' || s);
console.log(result);这篇好文章是转载于：学新通技术网
