javascript 判断是否为数字
 

function isNumberTest(str) {const method1 = (v) => {let exp = /^[+-]?\d*(\.\d*)?(e[+-]?\d+)?$/;// exp.test("+1.9"); // true// exp.test("-.1e11"); // truereturn exp.test(v) && str !== "";};const method2 = (v) => {return !isNaN(parseFloat(v)) && isFinite(v);};// const test = () => {//   console.log("null", isNumberTest(null));//   console.log("undefined", isNumberTest(undefined));//   console.log("NaN", isNumberTest(parseInt("a")));//   console.log("empty string", isNumberTest(""));//   console.log("123", isNumberTest("123"));//   console.log("123abc", isNumberTest("123abc"));//   console.log("0.1", isNumberTest("0.1"));//   console.log(0, isNumberTest(0));//   console.log(0.1, isNumberTest(0.1));//   console.log(-0.1, isNumberTest(-0.1));// };return method1(str);
}