Simplify my function (loop, array)?

Question

I have a function that is repeated a few times, and I believe it is possible to simplify and send variables from an array.

var i = masterdata.timing.split(',');
        var index = 0;
        for (index = 0; index < i.length; ++index) {
            $("#timing_" + i[index].trim()).prop('checked', true);
        }

    var i = masterdata.concern.split(',');
    var index = 0;
    for (index = 0; index < i.length; ++index) {
        $("#concern_" + i[index].trim()).prop('checked', true);
    }

    var i = masterdata.steps.split(',');
    var index = 0;
    for (index = 0; index < i.length; ++index) {
        $("#steps_" + i[index].trim()).prop('checked', true);
    }

Maybe just change the categories into a variable and send the catergories from an array?

var chkgroup = [
            'timing, concern, steps'
        ]

Answer 1

Your idea should work fine:

var i;
var index = 0;
var j = 0;
var chkgroup = ['timing', 'concern', 'steps'];
var currentGroup;

for (j = 0; j < chkgroup.length; ++j) {
    currentGroup = chkgroup[j];

    i = masterdata[currentGroup].split(',');

    for (index = 0; index < i.length; ++index) {
        $("#" + currentGroup + "_" + i[index].trim())
            .prop('checked', true);
    }        
}

If the chkgroup array really matches the object keys in masterdata, you could use an outer for..in loop instead:

var i;
var index = 0;
var currentGroup;

for (currentGroup in masterdata) {
    i = masterdata[currentGroup].split(',');

    for (index = 0; index < i.length; ++index) {
        $("#" + currentGroup + "_" + i[index].trim())
            .prop('checked', true);
    }        
}

Note that there's no order defined for for...in, so if you need to guarantee that you're iterating over the object properties in a certain order, it might be better to use the predefined array.

You could also get fancy with $.map:

var values = $.map(masterdata, function (i, currentGroup) {
    return $.map(i.split(','), function (val) {
        return $('#' + currentGroup + '_' + val.trim());
    });
});

$(values).prop('checked', true);