JS，如何在调用 String.prototype.replace() 的替换函数中访问 "this"

Question

我有这段代码：

class MyClass {
  constructor(text, pattern) {
    this.text = text;
    this.pattern = pattern;
  }

  run() {
    return this.text.replace(/(\d)/, this.replacer)
  }

  replacer(match, timeString, offset, string) {
    return this.pattern;
  }
}

这是我实际代码的简化示例。

当我运行:

var v = new MyClass("text 1 2", "X");
v.run();

我看到错误：

Uncaught TypeError: Cannot read properties of undefined (reading 'pattern')

如何在此替换函数中访问 this？

Answer 1

使用Function#bind设置this值，或使用调用this.replacer作为回调的箭头函数。

class MyClass {
  constructor(text, pattern) {
    this.text = text;
    this.pattern = pattern;
  }

  run() {
    return this.text.replace(/(\d)/, this.replacer.bind(this));
    // or return this.text.replace(/(\d)/, (...args) => this.replacer(...args));
  }

  replacer(match, timeString, offset, string) {
    return this.pattern;
  }
}
var v = new MyClass("text 1 2", "X")
console.log(v.run());

JS，如何在调用 String.prototype.replace() 的替换函数中访问 "this"

JS, how to access to "this" in a replacer function in a call to String.prototype.replace()

javascript

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