js对字符串的顺序截取

截取字符串前几位

var disName =‘123456’;
var shortName = disName.substring(0,5);
console.log(shortName);//打印结果：12345

截取字符串后几位

var disName =‘54321’;
var disLength = disName.length;
var shortName = disName.substring(disLength-2,disLength);
console.log(shortName);//打印结果：21