A reflection on the bug of JavaScript imitating snake

Bug phenomenon: Figure I

Figure I, Code analysis

Snake.prototype.move=function(food,map) {//the head moves first,      Switch( This. Direction) {              Case"Right":                 This. body[0].x +=1;  Break;  Case"Left":                    This. body[0].x-=1;  Break;  Case"Top":                    This. BODY[0].Y-=1;  Break;  Case"Bottom":                    This. BODY[0].Y +=1;  Break; }            varI= This. body.length-1;  for(i;i>0;i--){             This. body[i].x= This. body[i-1].x;//section X coordinates = = first section X coordinate             This. body[i].y= This. body[i-1].y; }

            Results of Run/    **   /

Figure II is correct

Figure II Code Analysis

Snake.prototype.move=function(food,map) {varI= This. body.length-1;  for(i;i>0;i--){             This. body[i].x= This. body[i-1].x;//section X coordinates = = first section X coordinate             This. body[i].y= This. body[i-1].y; }          //head back Move          Switch( This. Direction) {               Case"Right":                   This. body[0].x +=1;  Break;  Case"Left":                   This. body[0].x-=1;  Break;  Case"Top":                   This. BODY[0].Y-=1;  Break;  Case"Bottom":                   This. BODY[0].Y +=1;  Break; }   /*Run result this.body=[{x:3,y:2,color: "Red"}, {x:2,y:2,color: "Orange"}, {x:       1,y:2,color: "Orange"}]; this.body=[0 {x:4,y:2,color: "Red"}, 1 {x:3,y:2,color: "Orange"}, 2 {x:2,y:2,color: "Oran          GE "}]; */

Conclusion:

1,bug logic errors cause, remind oneself especially in learning things, clear logic realization principle, where data is produced, where is used.

2, debugging ability to get great exercise, this time from the discovery of the phenomenon, to keep trying behind the reasons, finally began to write the test code in the file, and finally find out exactly where the error, and experienced 1 hours or so.

3, the error is not terrible, terrible is not make mistakes, a little problem. Experience, not this time, make a mistake, and conquer it then you will.

A reflection on the bug of JavaScript imitating snake