如何将此文件读入变量？

with open("file.txt", "r") as file:
    content = file.read()

const fs = require("fs");
const content = fs.readFileSync("file.txt", "utf8");

File file = new File("file.txt");
String content = new String(Files.readAllBytes(file.toPath()));

#include <iostream>
#include <fstream>

int main() {
    std::ifstream file("file.txt");
    std::string content(
        (std::istreambuf_iterator<char>(file)),
        (std::istreambuf_iterator<char>()));
    std::cout << content;
    return 0;
}

fetch("file.txt")
  .then(response => response.text())
  .then(content => console.log(content));