我如何检查一个变量的类型是否为布尔类型?

我的意思是,有一些替代方案,比如:

if(jQuery.type(new Boolean()) === jQuery.type(variable))
      //Do something..

但这对我来说不太好。

有没有更清洁的方式来实现这个目标?


当前回答

The most readable: val === false || val === true. Also readable: typeof variable == typeof true. The shortest, but not readable at all: !!val === val. Explanation: [!!] The double exclamation mark converts the value into a Boolean. [===] The triple equals test for strict equality: both the type (Boolean) and the value have to be the same. If the original value is not a Boolean one, it won't pass the triple equals test. If it is a Boolean variable, it will pass the triple equals test (with both type & value). Tests: !!5 === 5 // false !!'test' === 'test' // false let val = new Date(); !!val === val // false !!true === true // true !!false === false // true

其他回答

The most readable: val === false || val === true. Also readable: typeof variable == typeof true. The shortest, but not readable at all: !!val === val. Explanation: [!!] The double exclamation mark converts the value into a Boolean. [===] The triple equals test for strict equality: both the type (Boolean) and the value have to be the same. If the original value is not a Boolean one, it won't pass the triple equals test. If it is a Boolean variable, it will pass the triple equals test (with both type & value). Tests: !!5 === 5 // false !!'test' === 'test' // false let val = new Date(); !!val === val // false !!true === true // true !!false === false // true

if(['true', 'yes', '1'].includes(single_value)) {
    return  true;   
}
else if(['false', 'no', '0'].includes(single_value)) {
    return  false;  
}

如果你有一个字符串

更新:以前的解决方案是更具体的,你可以选择哪个值你想考虑作为一个布尔值,你可以添加在正则表达式,如果你需要一个更通用的解决方案,不想添加一个库,然后检查下面的解决方案(从lodash的布尔)

function getTag(value) {
  if (value == null) {
    return value === undefined ? '[object Undefined]' : '[object Null]'
  }
  return toString.call(value)
}

function isObjectLike(value) {
  return typeof value === 'object' && value !== null
}

function isBoolean(value) {
  return value === true || value === false ||
    (isObjectLike(value) && getTag(value) == '[object Boolean]')
}

之前的解决方案 const isBoolean = (val) => { const boolValuesRegex = /true|false/// Add other /true|false|1|0|on|off/ 如果(val === undefined || val === null)返回false; .toLowerCase返回boolValuesRegex.test (val.toString () ()); } 常量值=(真的,假的,“真正的”,“假”,“真正的”,“假”,“sampletext”,1,定义,null , (() => {}), {}, []]; document.body.innerHTML = values。map(x => ' ${x} - ${isBoolean(x)} ') .join('</br>');

在nodejs中,通过使用node-boolify,我们可以使用isBoolean();

        var isBoolean = require('node-boolify').isBoolean;
        isBoolean(true); //true
        isBoolean('true'); //true
        isBoolean('TRUE'); //false
        isBoolean(1); //true
        isBoolean(2); //false
        isBoolean(false); //true
        isBoolean('false'); //true
        isBoolean('FALSE'); //false
        isBoolean(0); //true
        isBoolean(null); //false
        isBoolean(undefined); //false
        isBoolean(); //false
        isBoolean(''); //false

关于es2015箭头函数的另一个决策

const isBoolean = val => typeof val === 'boolean';