<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title></title> <script type="text/javascript"> /* 强转 */ /* 1.其他类型转为Number类型 */ var s1 = "10"; var s2 = "abc"; var b1 = false; var o1 = Object(10); var o2 = new Array(); o2[0]=1; o2[1]=2; var o3 = null; document.write("String转number，可转："+Number(s1)+"<br>");//10 document.write("String转number，不可转："+Number(s2)+"<br>");//Nan document.write("boolean转number，可转："+Number(b1)+"<br>");//0 document.write("Object转number=："+Number(o2)+"<br>");//若o2中只有o2[0]，则为1，若还有o2[1]，则为NaN document.write("null转number："+Number(o3)+"<br>");//0 /* 能转就转，不能转就为NaN， */ /* 2.其他类型转为boolean类型 */ var nb = 10; var sb = "abc"; var ob = new Object(1); var unb; //2.1Number转Boolean document.write("Number转Boolean："+Boolean(nb)+"<br>");//非零转成true，0转成false //2.2String转Boolean document.write("String转Boolean："+Boolean(sb)+"<br>");//非空转成true，空转成false //2.3Object转Boolean document.write("Object转Boolean："+Boolean(ob)+"<br>");//非null转成true，null转成false //2.4声明未赋值(undefined)转Boolean document.write("声明未赋值(undefined)转Boolean："+Boolean(unb)+"<br>");//false
</script> </head> <body> </body> </html>
<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title></title> <script type="text/javascript"> /* 3.boolean转String */ var b = true; document.write("Boolean转String："+typeof(b.toString())+"<br>");//String /* 4.String转Number */ var s = "10"; document.write("String转Number："+typeof(parseInt(s) )+"<br>");//number </script> </head> <body> </body> </html>