更新时间:2022-05-11 00:17:17
var arr = [ 'Car', 'Car', 'Truck', 'Boat', 'Truck' ];
var hist = {};
arr.map( function (a) { if (a in hist) hist[a] ++; else hist[a] = 1; } );
console.log(hist);
结果
{ Car: 2, Truck: 2, Boat: 1 }
这也有效:
hist = arr.reduce( function (prev, item) {
if ( item in prev ) prev[item] ++;
else prev[item] = 1;
return prev;
}, {} );