js如何判断两个对象相等?

对象当然不相等，相等的是对象的内容。

看你怎么定义“相等”，a == b判断的是a和b是否指向同一个对象。
如果比较它的数组是否相等，需要循环自己判断。

基本类型可以直接判断是否相等，引用类型就只能判断它们的内容是否相等，要判断两个对象是否相等需要自己在js里写一个判断规则的方法了

你那个a[0]和b[0]是两个obj，你要是真想要对比这个

var a=xxx
var b=xxx
consloe.log(a[0].id==b[0].id&&a[0].num==b[0].num)

 cmp = function( x, y ) { 
// If both x and y are null or undefined and exactly the same 
if ( x === y ) { 
 return true; 
} 

// If they are not strictly equal, they both need to be Objects 
if ( ! ( x instanceof Object ) || ! ( y instanceof Object ) ) { 
 return false; 
} 

//They must have the exact same prototype chain,the closest we can do is
//test the constructor. 
if ( x.constructor !== y.constructor ) { 
 return false; 
} 

for ( var p in x ) { 
 //Inherited properties were tested using x.constructor === y.constructor
 if ( x.hasOwnProperty( p ) ) { 
 // Allows comparing x[ p ] and y[ p ] when set to undefined 
 if ( ! y.hasOwnProperty( p ) ) { 
  return false; 
 } 

 // If they have the same strict value or identity then they are equal 
 if ( x[ p ] === y[ p ] ) { 
  continue; 
 } 

 // Numbers, Strings, Functions, Booleans must be strictly equal 
 if ( typeof( x[ p ] ) !== "object" ) { 
  return false; 
 } 

 // Objects and Arrays must be tested recursively 
 if ( ! Object.equals( x[ p ], y[ p ] ) ) { 
  return false; 
 } 
 } 
} 

for ( p in y ) { 
 // allows x[ p ] to be set to undefined 
 if ( y.hasOwnProperty( p ) && ! x.hasOwnProperty( p ) ) { 
 return false; 
 } 
} 
return true; 
};


objA={ 
 a:'123', 
 b:'456'
}; 
objB={ 
 a:'123', 
 b:'000'
}; 
var isEqual= cmp(objA, objB); 
 console.log(isEqual);  // false 不相同