问题
Is it possible to do something like this in JavaScript?
max = (max < b) ? b;
In other words, assign value only if the condition is true. If the condition is false, do nothing (no assignment). Is this possible?
回答1:
Don't use the ternary operator then, it requires a third argument. You would need to reassign max to max if you don't want it to change (max = (max < b) ? b : max).
An if-statement is much more clear:
if (max < b) max = b;
And if you need it to be an expression, you can (ab)use the short-circuit-evaluation of AND:
(max < b) && (max = b)
Btw, if you want to avoid repeating variable names (or expressions?), you could use the maximum function:
max = Math.max(max, b);
回答2:
An expression with ternary operator must have both values, i.e. for both the true and false cases.
You can however
max = (max < b) ? b : max;
in this case, if condition is false, value of max will not change.
回答3:
You can just set max to itself if the condition is false.
max = (max < b) ? b : max;
Or you can try using the && operator:
(max < b) && (max = b);
Or to keep your code simple, just use an if.
if(max < v) max = b;
回答4:
I think ternary is more suitable try this
(max < b) ? max = b : '';
回答5:
There isn't a specific operator that isn't the ternary operator, but you can use it like this:
max = (max < b) ? b : max;
回答6:
I think a better approach could be
max = Math.max(max, b)
回答7:
look:
(max < b) ? max = b : null;
it's going to work out, I think you wanna avoid using a colon, unfortunately, it won't happen
回答8:
You can do something like this:
(max < b) ? max = b : ''
来源：https://stackoverflow.com/questions/15009194/assign-only-if-condition-is-true-in-ternary-operator-in-javascript