04.JavaScript逻辑运算

• 计算运算符

    
        
        
        
    
    
        
结果查看
        

            
        
    
 

运行结果

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• 比较运算符

    
        
        
    
    
        
结果:
        
    

运行结果

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• Boolean对象

1. Boolean对象可以检查对象的逻辑结果(true/false)
2. Boolean对象可以将非逻辑值转换为逻辑值
3. 只有对象 无初始值,0,-0,null,"",false,undefined,NaN 返回false,其他返回true
4. 注意:字符串'0',"false"值是true,只有空字符串为false.

    
        
        
        
        
    
    
        

            

                
Boolean对象
                
代码:
                

                    
                    //新建boolean对象
                    var booEty = new Boolean();
                    //布尔值
                    var booDict={
                        "Boolean()":new Boolean(),
                        "Boolean(0)":new Boolean(0),
                        "Boolean(-0)":new Boolean(-0),
                        "Boolean(null)":new Boolean(null),
                        "Boolean('')":new Boolean(''),
                        "Boolean(false)":new Boolean(false),
                        "Boolean(undefined)":new Boolean(undefined),
                        "Boolean(NaN)":new Boolean(NaN),
                        "Boolean('0')":new Boolean('0'),
                        "Boolean(1)":new Boolean(1),
                        "Boolean('false')":new Boolean('false')
                    }
                    
                    objDisplay("dict01",booDict);
                    
                
              
                
结果:
                

                

                
            
               
        
       
    

image.png

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