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第 14 期(2019-05-21):类型判断 #16

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Description

@wingmeng

类型:基础知识
难度:★

实现 isObject(X), isString(X), isArray(X) 三个方法,用以判断是否为对应类型,返回布尔值

测试用例:

isObject([1, 2]);  // false
isString(123);  // false
isArray({a: 1});  // false

isObject({a: 1});  // true
isString('123');  // true
isArray([1, 2]);  // true

参考答案:

非常有价值的一段代码,类型判断的神码,函数柯里化的入门级教学代码。(来自 seajs 源码)

function isType(type) {
  return function(obj) {
    return Object.prototype.toString.call(obj) === '[object ' + type + ']'
  }
}

var isObject = isType('Object');
var isString = isType('String');
var isArray = Array.isArray || isType('Array');

Activity

  1. AMY-Y commented on May 22, 2019

    @AMY-Y
            function isObject(x){
                return x instanceof Object;
            }       
            function isString(x){
                return x instanceof String || typeof x == 'string';
            }       
            function isArray(x){
                return x instanceof Array;
            }  
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