一、substring()
str1='ABCDEFGHIJKLMNOPQRSTUVWXYZ';
document.write(str1.substring(2,5)+'<br/>');
document.write(str1.substring(5,2)+'<br/>');
document.write(str1.substring(5,-2)+'<br/>');
document.write(str1.substring(2,5)+'<br/>');
document.write(str1.substring(5,2)+'<br/>');
document.write(str1.substring(5,-2)+'<br/>');
输出
CDE
CDE
ABCDE
CDE
ABCDE
总结:string.substring(from,to)自动排序,若是有负值,则为0;参数是开始与结尾
二、substr()
str1='ABCDEFGHIJKLMNOPQRSTUVWXYZ';
document.write(str1.substr(2,5)+'<br/>');
document.write(str1.substr(5,2)+'<br/>');
document.write(str1.substr(5,-2)+'<br/>');
document.write(str1.substr(2,5)+'<br/>');
document.write(str1.substr(5,2)+'<br/>');
document.write(str1.substr(5,-2)+'<br/>');
输出
CDEFG
FG
FG
空值
总结:string.substr(start,length),不接受负值,参数是开始与截取的个数
三、slice()
str1='ABCDEFGHIJKLMNOPQRSTUVWXYZ';
document.write(str1.slice(2,5)+'<br/>');
document.write(str1.slice(5,2)+'<br/>');
document.write(str1.slice(5,-2)+'<br/>');
document.write(str1.slice(2,5)+'<br/>');
document.write(str1.slice(5,2)+'<br/>');
document.write(str1.slice(5,-2)+'<br/>');
输出
CDE
空值
FGHIJKLMNOPQRSTUVWX
FGHIJKLMNOPQRSTUVWX
总结:string.slice(from,to) 负值为从后往前数