count the number of elements in an array javascript
var arr = [10,20,30,40,50]; //An Array is defined with 5 instances
var len= arr.length; //Now arr.length returns 5.Basically, len=5.
console.log(len); //gives 5
console.log(arr.length); //also gives 5count number of each element in array javascript
var arr = [5, 5, 5, 2, 2, 2, 2, 2, 9, 4];
var counts = {};
for (var i = 0; i < arr.length; i++) {
var num = arr[i];
counts[num] ? counts[num] + 1 : 1;
}
console.log(counts[5], counts[2], counts[9], counts[4]);use .map to count length of each element in an array
var lengths = chars.map(function(word){
return word.length
})use .map to count length of each element in an array
var words = ['Hello', 'world'];
var lengths = words.map(function(word) {
return word + ' = ' + word.length;
});
console.log(lengths);typescript count array condition
let data = [ { "id": 1, "is_read": true, }, { "id": 2, "is_read": true, }, { "id": 3, "is_read": false, }, { "id": 4, "is_read": true, }, ],
length = data.filter(function(item){
return item.is_read;
}).length;
console.log(length)Copyright © 2021 Codeinu
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