返回包含条件的数组的长度

Question

function(people){

}
people([{name: 'John', age: 22},{name: 'paul', age: 23},{name: 'mathew', age: 24},])

How to return the length of an array consisting of person age more than 22 years old which should be 2.

Answer 1

You can use array reduce to count:

 function people(array){ return array.reduce((total, current)=>{ if(current.age>22) total = total +1; return total; },0); } console.log(people([{name: 'John', age: 22},{name: 'paul', age: 23},{name: 'mathew', age: 24},]));

Answer 2

Below is the functional programming approach to your question:

 const persons = [ {name: 'John', age: 22}, {name: 'paul', age: 23}, {name: 'mathew', age: 24} ] const over22 = persons.filter(person => person.age > 22) console.log('there are', over22.length, 'people aged over 22')

Hope this helps. Cheers,

Answer 3

Please try following :

function find_length(checkField, valueField, myArray) {
  for (var i = 0; i < myArray.length; i++) {
      if (myArray[i][checkField] == valueField) {
         return Object.keys(myArray[i]).length;
      }
  }
}

var myList = [{name: 'John', age: 22}, {name: 'paul', age: 23}, {name: 'mathew', age: 24},];
var ageObjLength = find_length('age', '22', myList );
alert("Length is " + ageObjLength);