JavaScript 中类型转换的完整指南：隐式与显式强制转换

let result = '5' + 1;
console.log(result);  // 输出: '51' (字符串)

let isValid = 'hello' == true;  // 隐式转换
console.log(isValid);  // 输出: true

let result = '5' == 5;
console.log(result);  // 输出: true (由于隐式转换)

let num = 123;
let str = String(num);  // 使用 String()
console.log(str);  // 输出: '123'

let bool = true;
let strBool = bool.toString();  // 使用 .toString()
console.log(strBool);  // 输出: 'true'

let str = '123';
let num = Number(str);
console.log(num);  // 输出: 123

let bool = true;
let numBool = +bool;  // 一元加号运算符
console.log(numBool);  // 输出: 1

let floatStr = '12.34';
let floatNum = parseFloat(floatStr);
console.log(floatNum);  // 输出: 12.34

let num = 0;
let bool = Boolean(num);  // 转换为 false
console.log(bool);  // 输出: false

let str = 'hello';
let boolStr = Boolean(str);  // 转换为 true
console.log(boolStr);  // 输出: true

let result = '5' + 1;
console.log(result);  // 输出: '51'

let result = '5' - 1;
console.log(result);  // 输出: 4 (数字)

let resultMul = '5' * 2;
console.log(resultMul);  // 输出: 10 (数字)

let result = '5' == 5;
console.log(result);  // 输出: true (发生类型转换)

let strictResult = '5' === 5;
console.log(strictResult);  // 输出: false (没有类型转换)

let result = 0 || 'hello';
console.log(result);  // 输出: 'hello' (0 为假值, 'hello' 为真值)

let resultAnd = 1 && 0;
console.log(resultAnd);  // 输出: 0 (因为 0 为假值)

let value = "";
if (value) {
  console.log("真值");
} else {
  console.log("假值");  // 输出: 假值 (因为 "" 为假值)
}

let num = Number(null);
console.log(num);  // 输出: 0

let num = Number(undefined);
console.log(num);  // 输出: NaN

let bool = Boolean(null);
console.log(bool);  // 输出: false

let num = 123;
let str = num.toString();  // 将数字转换为字符串
console.log(str);  // 输出: '123'