Question

array.length总是返回0 .... 它返回0甚至一些项目添加到数组中......

 function validate () { 

  error = new Array();

  if(req.body.category_id==""){ 
    error['category_id'] = "Please select category";
  }

  if(req.body.text==""){ 
    error['text'] = "Enter the word";
  }

  if(!(req.body.email!="" && req.body.email.test(/@/))){ 
    error['email'] = "Invalid email id";
  }

  if((req.session.number1+req.session.number2)!=req.body.captcha){ 
    error['captcha'] = "Captcha verification failed";
  }  

 console.log(error.length);
 console.log(error['category_id']);

  if(error.length){ 
    return false;   
  }else{ 
    return true;
  }
}

result of the console.log
//0
//Please select category

Answer 1

Array.length仅计算键为 numeric 的值。您使用 strings 作为键，因此您的长度始终为0.虽然合法，（因为Arrays是Objects），这很容易混淆，并且不适合数组。

正如@Sudhir建议的那样，使用“对象”或“哈希”：{}表示法。更清楚。（虽然我不同意他用Object.prototype修改）

Answer 2

Javascript没有关联数组，使其成为对象：

//function to get size of object
Object.prototype.size = function(obj) {
    var size = 0, key;
    for (key in obj) {
        if (obj.hasOwnProperty(key)) size++;
    }
    return size;
};
var error = {}; //object
if(req.body.category_id==""){ 
    error['category_id'] = "Please select category";
}
...
//rest of your code
if( Object.size(error) ){ //check if we have error
    return false;   
}else{ 
    return true;
}

//check the size of object
console.log(  Object.size(error) );
console.log(error['category_id']);

Answer 3

var error = function(){};
error.prototype.test=[1,2,3];  //1,2,3 only example
console.log(new error().test.length);

使用JavaScript.prototype

但是使用此函数创建的对象将在其原型链中具有此属性（prototype property error指向已定义test属性的对象。

node.js Array.length问题

3 个答案: