1.将数值类型转换成字符串类型
隐式转换
1 <!DOCTYPE html> 2 <html lang="en"> 3 <head> 4 <meta charset="UTF-8"> 5 <title>流浪者</title> 6 7 </head> 8 <body> 9 10 <script> 11 var a = 123; 12 var b = '123'; 13 console.log(typeof (a + b)); //数字和字符串相加，默认转换成字符串类型 14 </script> 15 16 </body> 17 </html>
强制类型转换
1 <!DOCTYPE html> 2 <html lang="en"> 3 <head> 4 <meta charset="UTF-8"> 5 <title>流浪者</title> 6 7 </head> 8 <body> 9 10 <script> 11 var n = 123; 12 var str1 = String(n); 13 console.log(typeof str1); 14 15 var str2 = n.toString(); 16 console.log(typeof str2); 17 </script> 18 19 </body> 20 </html>
2.将字符串类型转换成数值类型
1 <!DOCTYPE html> 2 <html lang="en"> 3 <head> 4 <meta charset="UTF-8"> 5 <title>流浪者</title> 6 7 </head> 8 <body> 9 10 <script> 11 var stringNum = '755.24hffjgi'; 12 var Num = Number(stringNum); 13 console.log(Num); 14 console.log(typeof Num); 15 16 // parseInt()可以解析一个字符串，并返回一个整数 17 console.log(parseInt(stringNum)); 18 console.log(parseFloat(stringNum)); 19 </script> 20 21 </body> 22 </html>
3.任何数据类型都可以转换成Boolean类型
1 <!DOCTYPE html> 2 <html lang="en"> 3 <head> 4 <meta charset="UTF-8"> 5 <title>流浪者</title> 6 7 </head> 8 <body> 9 10 <script> 11 var a1 = '135'; 12 var a2 = 0; 13 var a3 = -111; 14 var a4 = NaN; 15 var a5 = Infinity; 16 var a6; 17 var a7 = null; 18 19 console.log(Boolean(a1)); 20 console.log(Boolean(a2)); 21 console.log(Boolean(a3)); 22 console.log(Boolean(a4)); 23 console.log(Boolean(a5)); 24 console.log(Boolean(a6)); 25 console.log(Boolean(a7)); 26 </script> 27 28 </body> 29 </html>
作者：流浪者
日期：2019-09-03