A plurality of loop condition problem (logical AND, logical OR, operator precedence)

 Loop set a number of conditions, sometimes not getting what the desired result, here is my clear priority for operators, due to the wrong summary:

1 <Script of the type = "text / JavaScript">
 2      var str = prompt ( "Do you love me?" );
 3      the while (! Str = "I love you" & "I love you!" ) {
 4          str = prompt ( "do you love me?" );
 5      }
 6 </ Script>

Want to enter, "I love you" and "I love you!" Can be the end of the cycle.

But! = Higher precedence than &&, ||, the above code will first execute str! = "I love you", if it is ture, was true && "I love you!" To return to "I love you!" "I love you!" as ture, the cycle continues. If the front is false (type "I love you"), false && "I love you!", Returns false, the loop ends. That second "I love you!" Has been true, does not make sense. The logic input is only "I love you" cycle to end.

PS: (0, "", ", null, undefined, NaN is false, the rest are true)

change into:

1 <Script of the type = "text / JavaScript">
 2      var str = prompt ( "Do you love me?" );
 3      the while (! Str = "I love you" && str = "I love you!"! ) {
 4          str = prompt ( "do you love me?" );
 5      }
 6 </ Script>

To perform two! =, And then && operator. Two conditions can be used. Logically that is, enter "I love you" or "I love you!", You can end the cycle.

Reanalysis of the logical OR:

<Script of the type = "text / JavaScript">
      var str = prompt ( "Do you love me?" );
      the while (! "! I love you" str = "I love you" || ) { 
         str = prompt ( "you I love you "? ); 
     }
 </ Script>

If the input other than "I love you", the true || "I love you!", Returns true, the loop continues. If you enter "I love you", the false || "I love you!" To return to "I love you!", The result was true, the cycle continues. Logically, no matter what you type, the cycle will not stop.

<Script of the type = "text / JavaScript">
      var str = prompt ( "Do you love me?" );
      the while (!! str = "I love you" || str = "I love you!" ) { 
         str = prompt ( "do you love me?" ); 
     }
 </ Script>

Here is the logic, only the input value is "I love you", and for "I love you!" To end the cycle. The string does not have one, so there is no sense.

Knowledge summarized as two points:

　　1. 0, "", ", null, undefined, NaN Boolean value false, the rest are true

　　2. JS operator precedence  , "! =" && again higher priority than || 

priority	Operation type	Relevance	Operators
20	Parentheses	n/a	( ... )
19	Member Access	From left to right	... . ...
19	Member Access to be calculated	From left to right	...[ ... ]
19	new (with the parameter list)	n/a	new ... ( ... )
19	Function call	From left to right	... ( ... )
18	new (no parameter list)	From left to right	new ...
17	Postincrement (after operator)	n/a	... ++
17	Post-decrement (operator after)	n/a	... --
16	Logical NOT	From right to left	! ...
16	Non-bit	From right to left	~ ...
16	Adding one yuan	From right to left	+ ...
16	Unary minus	From right to left	- ...
16	Pre-increment	From right to left	++ ...
16	Pre-decrement	From right to left	-- ...
16	typeof	From right to left	typeof ...
16	void	From right to left	void ...
16	delete	From right to left	delete ...
15	power	From right to left	... ** ...
14	multiplication	From left to right	... * ...
14	division	From left to right	... / ...
14	Modulo	From left to right	... % ...
13	addition	From left to right	... + ...
13	Subtraction	From left to right	... - ...
12	Bitwise left shift	From left to right	... << ...
12	Bitwise Right Shift	From left to right	... >> ...
12	Unsigned right shift	From left to right	... >>> ...
11	Less than	From left to right	... < ...
11	Less than or equal	From left to right	... <= ...
11	more than the	From left to right	... > ...
11	greater or equal to	From left to right	... >= ...
11	in	From left to right	... in ...
11	instanceof	From left to right	... instanceof ...
10	equal sign	From left to right	... == ...
10	Non-equal sign	From left to right	... != ...
10	Full equal sign	From left to right	... === ...
10	Part-equal sign	From left to right	... !== ...
9	Bitwise AND	From left to right	... & ...
8	Bitwise XOR	From left to right	... ^ ...
7	Bitwise or	From left to right	... | ...
6	逻辑与	从左到右	... && ...
5	逻辑或	从左到右	... || ...
4	条件运算符	从右到左	... ? ... : ...
3	赋值	从右到左	... = ...
3	赋值	从右到左	... += ...
3	赋值	从右到左	... -= ...
3	赋值	从右到左	... /= ...
3	赋值	从右到左	...% = ...
3	赋值	从右到左	... *= ...
2	yield	从右到左	yield ...
2	yield*	从右到左	yield* ...
1	展开运算符	从左到右	... ...
0	逗号	从左到右	... , ...