如何基于值而不是键迭代对象数组？

Question

I know I can iterate over an object array and check values by utilizing the key. But is there a way to check the key by looking at the value? I use jQuery although I think this is simply a javascript question.

var j = [
    {hello : 1},
    {hello : 2},
    {bye : 3}
]


$.each(j, function(i,item){
    if(item.hello==1) alert("hello");
});

How do I make the alert dependent on the value being 1, irrespective of what key it is?

Answer 1

You would have to iterate through each key in the array, like this:

$.each(j, function(i,item){
    for (var key in item) {
         if (item[key]==1) {
             alert("it said hello");
         }
    }
});

But why not store it in another format, if that's how you'd like to use it? ie,

var j = [
    [hello, 1],
    [hello, 2],
    [bye, 3]
]

Answer 2

There's the for-of loop proposed in ECMAScript 6.

for (item of j){
    if(item.hello==1){
         alert("it said hello");
    }
}

This feature appeared in Firefox 31 and it is shipped with Chrome 38. IE doesn't implement it. Don't know about other browsers.

Answer 3

Try

var j = [
    {hello : 1},
    {hello : 2},
    {bye : 3}
];
$.each(j, function(i, item){;
    $.each(item, function(key, value) {
      if (value === 1) {
        alert("it said hello")
      }
    })
});

Answer 4

For expample:

var j = [ {hello : 1}, {hello : 2}, {bye : 3} ];
for (var i in j)
{
    for  (var s in j[i])
    {
        if (j[i][s] == 1)
        {
            alert("it said hello");
        }
    }
}