obj[key]和0bj.['key']

本文探讨了JavaScript中对象属性的两种主要赋值方法:直接属性访问和使用方括号表示法。通过实例展示了如何使用这两种方法为对象添加属性,并讨论了它们之间的区别。

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 <script>

// obj.key = value

        let obj ={ };
        //给obj添加name属性
        obj.name = '张三';
        console.log(obj)	// {name: "张三"}

        let aa ={
            name: "李四",
            age: 22
        };

// obj[key] = value

        //aa[home] = "韶关" ; 
        // console.log(aa);    // 报home is not defined错误,因为aa对象里没有home属性,不能这样为对象添加属性

	    //aa[2] = "韶关" ; 
        // console.log(aa);    // aa = {2:"韶关",age: 22,name: "李四"}

// obj[‘key’] = value

	    // 为aa对象添加属性: obj['key'] = value (key必须是字符串,加引号)
	    aa['home'] = "韶关" ;
        console.log( aa);     // aa = {age: 22,home: "韶关",name: "李四"}
   
    	总结: obj.key = value 与 obj['key'] = value都是为对象添加属性
 </script>
--------------------------------------------------------------------------- KeyError Traceback (most recent call last) ~\AppData\Local\Temp\ipykernel_12396\356241790.py in <module> 3 if (df['应发库'][i]!="sz"and df['应发库'][i]!="cs"and df['应发库'][i]!="sy"and df['应发库'][i]!="sh"and df['应发库'][i]!="cd"and df['应发库'][i]!="xa"and df['应发库'][i]!="km"and df['应发库'][i]!="jn"and df['应发库'][i]!="bj"): 4 droplist.append(i) ----> 5 df2=df1.drop(labels=droplist,axis=0) ~\AppData\Local\anaconda3\envs\tensorflow\lib\site-packages\pandas\util\_decorators.py in wrapper(*args, **kwargs) 309 stacklevel=stacklevel, 310 ) --> 311 return func(*args, **kwargs) 312 313 return wrapper ~\AppData\Local\anaconda3\envs\tensorflow\lib\site-packages\pandas\core\frame.py in drop(self, labels, axis, index, columns, level, inplace, errors) 4911 level=level, 4912 inplace=inplace, -> 4913 errors=errors, 4914 ) 4915 ~\AppData\Local\anaconda3\envs\tensorflow\lib\site-packages\pandas\core\generic.py in drop(self, labels, axis, index, columns, level, inplace, errors) 4148 for axis, labels in axes.items(): 4149 if labels is not None: -> 4150 obj = obj._drop_axis(labels, axis, level=level, errors=errors) 4151 4152 if inplace: ~\AppData\Local\anaconda3\envs\tensorflow\lib\site-packages\pandas\core\generic.py in _drop_axis(self, labels, axis, level, errors) 4183 new_axis = axis.drop(labels, level=level, errors=errors) 4184 else: -> 4185 new_axis = axis.drop(labels, errors=errors) 4186 result = self.reindex(**{axis_name: new_axis}) 4187 ~\AppData\Local\anaconda3\envs\tensorflow\lib\site-packages\pandas\core\indexes\base.py in drop(self, labels, errors) 6015 if mask.any(): 6016 if errors != "ignore": -> 6017 raise KeyError(f"{labels[mask]} not found in axis") 6018 indexer = indexer[~mask] 6019 return self.delete(indexer) KeyError: '[357143] not found in axis'
06-03
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