Given a JavaScript array of objects, how can I get the key and value of each object?
The code below shows what I'd like to do, but obviously doesn't work:
var top_brands = [ { 'Adidas' : 100 }, { 'Nike' : 50 }];
var brand_options = $("#top-brands");
$.each(top_brands, function() {
brand_options.append($("<option />").val(this.key).text(this.key + " " + this.value));
});
So, how can I get this.key and this.value for each entry in the array?
Change your object.
var top_brands = [
{ key: 'Adidas', value: 100 },
{ key: 'Nike', value: 50 }
];
var $brand_options = $("#top-brands");
$.each(top_brands, function(brand) {
$brand_options.append(
$("<option />").val(brand.key).text(brand.key + " " + brand.value)
);
});
As a rule of thumb:
'Adidas', 'Nike', 100 and 50 are data.There are no semantics in {Nike: 50}. What's "Nike"? What's 50?
{key: 'Nike', value: 50} is a little better, since now you can iterate an array of these objects and values are at predictable places. This makes it easy to write code that handles them.
Better still would be {vendor: 'Nike', itemsSold: 50}, because now values are not only at predictable places, they also have meaningful names. Technically that's the same thing as above, but now a person would also understand what the values are supposed to mean.
{Nike: 50} might be smaller, but it has no semantic value. Additionally for.. in is not a safe way of iterating objects and you should not use it.$.each(top_brands, function() {
var key = Object.keys(this)[0];
var value = this[key];
brand_options.append($("<option />").val(key).text(key + " " + value));
});
If this is all the object is going to store, then best literal would be
var top_brands = {
'Adidas' : 100,
'Nike' : 50
};
Then all you need is a for...in loop.
for (var key in top_brands){
console.log(key, top_brands[key]);
}
$.each(top_brands, function(index, el) {
for (var key in el) {
if (el.hasOwnProperty(key)) {
brand_options.append($("<option />").val(key).text(key+ " " + el[key]));
}
}
});
But if your data structure is var top_brands = {'Adidas': 100, 'Nike': 50};, then thing will be much more simple.
for (var key in top_brands) {
if (top_brands.hasOwnProperty(key)) {
brand_options.append($("<option />").val(key).text(key+ " " + el[key]));
}
}
Or use the jquery each:
$.each(top_brands, function(key, value) {
brand_options.append($("<option />").val(key).text(key + " " + value));
});
for (var i in a) {
console.log(a[i],i)
}
Object.keys(top_brands).forEach(function(key) {
var value = top_brands[key];
// use "key" and "value" here...
});
Btw, note that Object.keys and forEach are not available in ancient browsers, but you should use some polyfill anyway.
for...in, but the semantics of your loop are wrong as it stands.var top_brands = {'Adidas': 100, 'Nike': 50};