1、该字符串为全数字
var s = '123';
a = s.substring(0,1); //str
console.log(a)
结果:1
2、该字符串是字母+数字
function getNum(str) {
var pattern = new RegExp("[0-9]+");
var num = str.match(pattern);
return num;
}
function execute(){
var inputStr = "asd2xde3";
var x = getNum(inputStr);
document.write(x)
} execute()
结果:2