var arr = [{code:'A', number: 1}, {code:'A', number: 2}, {code:'B', number: 3 }]
How can I get a number of objects that has certain key in above array?
For example, The number of code: 'A' objects is 2.
How to get it?
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2 Answers
filter will iterate through the array and execute your callback function. The callback function needs to evaluate to a boolean for the value to return.
var arr = [{code:'A', number: 1}, {code:'A', number: 2}, {code:'B', number: 3 }]
arr.filter(function(x) { return x.code === 'A'}).length
Comments
Iterate through the array and store the informations like count and corresponding numbers in an object structure.
var arr = [{code:'A', number: 1}, {code:'A', number: 2}, {code:'B', number: 3 }];
var obj = {};
debugger;
for (var i =0, len = arr.length; i < len; i += 1) {
ele = arr[i];
code = ele.code
if (!obj[code]) {
obj[code] = {
count: 0,
number: []
};
}
obj[code].count += 1;
obj[code].number.push(ele.number);
}
function getCount(code) {
return obj[code].count;
}
console.log(getCount('A')); // 2
console.log(getCount('B')); // 1
console.log(obj);