哦?使用正则表达式!：）

function isInteger(val) {
  return val.match(/^[0-9]$/)
}

function isFloat(val) {
  return val.match(/^[0-9]*/\.[0-9]+$/)
}

最好的方法是使用isNaN +类型转换:

更新的all-in方法:

function isNumber(n) { return !isNaN(parseFloat(n)) && !isNaN(n - 0) }

使用regex也一样:

function isNumber(n) { return /^-?[\d.]+(?:e-?\d+)?$/.test(n); } 

------------------------

isNumber('123'); // true  
isNumber('123abc'); // false  
isNumber(5); // true  
isNumber('q345'); // false
isNumber(null); // false
isNumber(undefined); // false
isNumber(false); // false
isNumber('   '); // false

效率测试

我知道我该怎么用…

isNaN(parseFloat(n)) && !isNaN(n - 0)} 函数isNumberRE (n){返回/ ^ - ? (\ d。)+ (?:e - ? \ d +) ?美元/ test (n);｝ function test(fn, timerLabel) { console.time (timerLabel) For (i = 0;I < 1000000;我+ +){ const num = Math.random() * 100 const isNum = fn(num) ｝ console.timeEnd (timerLabel) ｝ test(isNumber， "Normal way") test(isNumberRE， "RegEx方式")

Normal way: 25.103271484375 ms
RegEx way: 334.791015625 ms

function IsNumeric(num) {
    return ((num >=0 || num < 0)&& (parseInt(num)==num) );
}

或者只使用isNaN()的倒数:

if(!isNaN(data))
  do something with the number
else
  it is a string

是的，使用jQuery的$. isnumeric()更有趣。

最好的方法是:

function isNumber(num) {
  return (typeof num == 'string' || typeof num == 'number') && !isNaN(num - 0) && num !== '';
};

这满足以下测试用例:

assertEquals("ISNUMBER-True: 0", true, isNumber(0));
assertEquals("ISNUMBER-True: 1", true, isNumber(-1));
assertEquals("ISNUMBER-True: 2", true, isNumber(-500));
assertEquals("ISNUMBER-True: 3", true, isNumber(15000));
assertEquals("ISNUMBER-True: 4", true, isNumber(0.35));
assertEquals("ISNUMBER-True: 5", true, isNumber(-10.35));
assertEquals("ISNUMBER-True: 6", true, isNumber(2.534e25));
assertEquals("ISNUMBER-True: 7", true, isNumber('2.534e25'));
assertEquals("ISNUMBER-True: 8", true, isNumber('52334'));
assertEquals("ISNUMBER-True: 9", true, isNumber('-234'));

assertEquals("ISNUMBER-False: 0", false, isNumber(NaN));
assertEquals("ISNUMBER-False: 1", false, isNumber({}));
assertEquals("ISNUMBER-False: 2", false, isNumber([]));
assertEquals("ISNUMBER-False: 3", false, isNumber(''));
assertEquals("ISNUMBER-False: 4", false, isNumber('one'));
assertEquals("ISNUMBER-False: 5", false, isNumber(true));
assertEquals("ISNUMBER-False: 6", false, isNumber(false));
assertEquals("ISNUMBER-False: 7", false, isNumber());
assertEquals("ISNUMBER-False: 8", false, isNumber(undefined));
assertEquals("ISNUMBER-False: 9", false, isNumber(null));