finding whether a value exists in a javascript object with jquery

Question

I am trying to determine whether a object contains a specific value so that I can be sure not append the value I am looking for more than once and prevent recursion.

I have tried lots of methods but can't get any of them to work:

data = [
  {val:'xxx',txt:'yyy'},
  {val:'yyy',txt:'aaa'},
  {val:'bbb',txt:'ccc'}
];

console.log(jQuery.grep(data, function(obj){
    return obj.txt === "ccc";
}));
$.map(data, function(el) { 
    if(el.txt === 'ccc') 
        console.log('found')
});

Can this be done with map() grep() or inArray() or do I really have to loop through the entire array looking for the value ??

Answer 1

data is an array containing multiple objects, so you'll need to specify the index of the array you wish to look in:

data[0].val === 'xxx';
data[1].val === 'yyy';
data[2].txt === 'ccc';

---

As an update to your function, what's wrong with $.each ? You're looping anyway with map or grep, so you may as well just be honest about it :P You can loop with for as well, but I'm exampling with $.each as it's almost identical to your current code.

$.each(data, function(el) { 
  if(el.txt === 'ccc') 
    console.log('found')
});

Answer 2

You will have to iterate the whole array as it's an array of objects, and comparing objects is done by the references not by the values.

for (var i = 0; i < data.length; i++){
    if (data[i].val == 'something')
        doSomething();
}

Answer 3

If you wish to avoid all this calculations yourself, there is a utility plugin underscore.js , which has lots of helper.

One of the helpers you are looking for http://underscorejs.org/#contains .

Answer 4

var stExist=$.inArray(reqelement, dataArray)