Question

I have a number of Javascript objects.

I want a simple ‘for loop’ (in JS) that prints out the key:value pairs within each object.

I’ve shown what I’ve done below (and here it is in a FIDDLE), but the variable ‘thisvar’ isn’t working.

I’m obviously missing something really simple – can you point out what it is?

Thanks

// declare objects
var variant1 = {};
var variant2 = {};

variant1['a'] = 'apple';
variant1['b'] = 'orange';
variant1['c'] = 'pear';

variant2['a'] = 'red';
variant2['b'] = 'green';
variant2['c'] = 'blue';

// run through each object
for (i=1; i<3; i++){
    var thisvar = variant+i;
    for(var newindex in thisvar) {
        var name = newindex;
        var contents = thisvar[newindex];
        alert(name+'='+contents);
    }
}

​

Answer 1

// declare objects
var container = {
    variant1: {}
    variant2: {}
}

container.variant1['a'] = 'apple';
container.variant1['b'] = 'orange';
container.variant1['c'] = 'pear';

container.variant2['a'] = 'red';
container.variant2['b'] = 'green';
container.variant2['c'] = 'blue';

// run through each object
for (var i = 1; i < 3; i++){
    for (prop in container["variant"+i]){
         if (variant.hasOwnProperty(prop)){
            alert(prop+'='+var[prop]);
         }
    }
}

As pointed out in the comments below, if you want to numerically iterate over the properties, you’re better off just using an array:

// declare objects
var variants = [{},{}];

variants[0]['a'] = 'apple';
variants[0]['b'] = 'orange';
variants[0]['c'] = 'pear';

variants[1]['a'] = 'red';
variants[1]['b'] = 'green';
variants[1]['c'] = 'blue';

// run through each object
for (var i = 0; i < 2; i++){
    for (prop in variants[i]){
         if (variant.hasOwnProperty(prop)){
            alert(prop+'='+var[prop]);
         }
    }
}