&& 和 || 有什么区别在 JavaScript 术语中？

Question

My classmate used "||" instead of "&&" for an if statement, but the result is the same. I tried to understand the differences by reading the article but I can't seem to understand them. I would appreciate if anyone can explain in an easy way...Thank you!

Answer 1

&& is and operator and || is or operator && work as

1 && 1= 1
1 && 0 = 0
0 && 1 = 0
0 && 0 = 0

|| work as

1 || 1= 1
1 || 0 = 1
0 || 1 = 1
0 || 0 = 0

where 1 , 0 are true and false we can understand it by the following example

suppose we have a code

if(1==1 && 2==2){}

so 1==1 is true means 1 and 2==2 is true means 1, so && operator work like this 1 && 1 =1 hence the result will be true and execute if statement

Answer 2

You could replace logical OR || with logical AND && and vice versa, by using De Morgan's laws :

!(a && b) = !a || !b 
!(a || b) = !a && !b

If you have

if (a || b)

you could use this without OR

if (!(!a && !b))