更好的方法来检查字典上的所有值是否都是真的？

Question

Ok, this is what i got:

var matchgrid = {
    "a1":[false, 0], "a2":[false, 0], "a3":[false, 0],
    "b1":[false, 0], "b2":[false, 0], "b3":[false, 0],
    "c1":[false, 0], "c2":[false, 0], "c3":[false, 0]};

var keys = Object.keys(matchgrid);

var ch = 0;

for (i=0;i<9;i++) {
        if (matchgrid[keys[i]][0] === false) {
            ch += 1;
        } else if (matchgrid[keys[i]][0] === true) {
            ch -= 1;
        }
    }

//then check it with:

if (ch === 9) {
    //do something
} else { 
    //do something else
}

as you can see, its a dictionary with arrays as values and i want to know if the first value of the all the keys is false , true or mixed, this works fine, but i'm sure that there's a better way to do it, any help?

Answer 1

Your native JavaScript approach is fine. Rather than storing the sum you may just store a boolean, start it as true, then if you see a false, set it to false. Then rather than check ch == 9 just check for the boolean.

However, if you can use underscore.js (which has a lot of useful functions for lists), one of those functions is called every that checks if every item passes the truth test. Then it becomes as simple as this

_.every(matchgrid, function(item) {
     return item[0];
})

Even shorter, and a little fancier:

_.every(matchgrid, _.first); // will return true if all elements are true

Answer 2

var ch = 0;

var result;
for (i=0;i<9;i++) {
        result = matchgrid[keys[i]][0];
        if (result) {
            break;
        } 
    }

// result will be false if they are all false