在javascript中解析字符串

var str = "123";
var num = parseInt(str);
console.log(num); // 输出：123

var str = "3.14";
var num = parseFloat(str);
console.log(num); // 输出：3.14

var str1 = "true";
var bool1 = Boolean(str1);
console.log(bool1); // 输出：true

var str2 = "false";
var bool2 = Boolean(str2);
console.log(bool2); // 输出：true

var str3 = "";
var bool3 = Boolean(str3);
console.log(bool3); // 输出：false

var jsonStr = '{"name":"John","age":30,"city":"New York"}';
var obj = JSON.parse(jsonStr);
console.log(obj.name); // 输出：John
console.log(obj.age); // 输出：30
console.log(obj.city); // 输出：New York

var dateStr = "2022-01-01";
var timestamp = Date.parse(dateStr);
console.log(timestamp); // 输出：1640995200000