js 正規表現が1-2個の整数、または小数点以下2桁までに制限されている。

<script type="text/javascript"> 
//1, can only input numbers or decimal points integers only, integers plus decimals
var reg1=/(^[0-9]{1,2}$)|(^[0-9]{1,2}[\.] {1}[0-9]{1,2}$)/;
console.log(reg1.test("")+" empty string false");
console.log(reg1.test("1")+" 1 true");
console.log(reg1.test("10")+" 10 true");
console.log(reg1.test("10.")+" 10. false");
console.log(reg1.test("100")+" 100 false");
console.log(reg1.test("100.1")+" 100.1 false");
console.log(reg1.test("10.1")+" 10.1 ture");
console.log(reg1.test("10.10")+" 10.10 true");
console.log(reg1.test("10.101")+" 10.101 false");
console.log(reg1.test("0.101")+" 0,101 false");
console.log(reg1.test("110.101")+" 110.101 false");
console.log(reg1.test("a")+" a false");
console.log(reg1.test("*")+" * false");
console.log(reg1.test("*")+" * false"); console.log(reg1.test(". ")+" . false");
</script> 

// must start with a number and end with a number, can contain a comma in between, if there is only one number it can only be a number
  var regx1=/(^[0-9]{1,}[0-9,]{0,}[0-9]{1,}$)|(^[0-9]{1}$)/;

var reg = /^[1-9]\d{0,3}\. \d$/ ; //first digit (1-9), zero to three digits in the middle, followed by a dot, and one decimal digit after the dot (0-9)
var reg = /^[1-9]\d{0,2}\. \d{2}$/; //first place (1-9), zero to two digits in the middle, followed by the dot, and two decimal places after the dot (0-9)
var reg = /^[1-9]\d{1,4}$/; //first place (1-9), middle to end one to four digits, no decimals
var reg = /^[0]\. \d{2,4}$/; //first (0), followed by dot, two to four decimal places after the dot (0-9)
//Written together, they are connected by the '|' symbol, which means or, either condition is met