⭐⭐⭐Convert HTML Entities

https://forum.freecodecamp.org/t/freecodecamp-challenge-guide-convert-html-entities/16007

转实体

  const htmlEntities = {
    "&": "&",
    "<": "&lt;",
    ">": "&gt;",
    '"': "&quot;",
    "'": "&apos;"
  };

使用encodeURIComponent(‘ % ‘)

转成了%20%26%20

Convert HTML Entities

Convert the characters &, <, >, " (double quote), and ' (apostrophe), in a string to their corresponding HTML entities.

使用split,map,join

function convertHTML(str) {
    const htmlEntities = {
    "&": "&",
    "<": "&lt;",
    ">": "&gt;",
    '"': "&quot;",
    "'": "&apos;"
  };
  return str.split("").map(x=>htmlEntities[x]||x).join('');
}
console.log(
convertHTML("Dolce & Gabbana")
)

join()默认用的是逗号,连接的

要想使用空字符串连接,需要使用’’

使用replace,replace第二个参数可以是函数

function convertHTML(str) {
  // Use Object Lookup to declare as many HTML entities as needed.
  const htmlEntities = {
    "&": "&",
    "<": "&lt;",
    ">": "&gt;",
    '"': "&quot;",
    "'": "&apos;"
  };
  // Using a regex, replace characters with it's corresponding html entity
  return str.replace(/([&<>\"'])/g, match => htmlEntities[match]);
}
// test here
convertHTML("Dolce & Gabbana");

使用switch

function convertHTML(str) {
  // Split by character to avoid problems.
  var temp = str.split("");
  // Since we are only checking for a few HTML elements, use a switch
  for (var i = 0; i < temp.length; i++) {
    switch (temp[i]) {
      case "<":
        temp[i] = "&lt;";
        break;
      case "&":
        temp[i] = "&amp;";
        break;
      case ">":
        temp[i] = "&gt;";
        break;
      case '"':
        temp[i] = "&quot;";
        break;
      case "'":
        temp[i] = "&apos;";
        break;
    }
  }
  temp = temp.join("");
  return temp;
}
//test here
convertHTML("Dolce & Gabbana");