检查对象是否为空的最快方法是什么?
有没有比这更快更好的方法:
function count_obj(obj){
var i = 0;
for(var key in obj){
++i;
}
return i;
}
当前回答
var x= {}
var y= {x:'hi'}
console.log(Object.keys(x).length===0)
console.log(Object.keys(y).length===0)
true
false
http://jsfiddle.net/j7ona6hz/1/
其他回答
if (Object.getOwnPropertyNames(obj1).length > 0)
{
alert('obj1 is empty!');
}
这是我的解决方案
function isEmpty(value) {
if(Object.prototype.toString.call(value) === '[object Array]') {
return value.length == 0;
} else if(value != null && typeof value === 'object') {
return Object.getOwnPropertyNames(value).length == 0;
} else {
return !(value || (value === 0));
}
}
解围球
不需要图书馆。
function(){ //must be within a function
var obj = {}; //the object to test
for(var isNotEmpty in obj) //will loop through once if there is a property of some sort, then
return alert('not empty')//what ever you are trying to do once
return alert('empty'); //nope obj was empty do this instead;
}
快速联机'dictionary'-objects:
function isEmptyDict(d){for (var k in d) return false; return true}
function isEmpty( o ) {
for ( var p in o ) {
if ( o.hasOwnProperty( p ) ) { return false; }
}
return true;
}
