Angular Typescript looping through array of objects to find the count

Question

I need help not sure what I'm missing. I am trying to loop through an array of objects in Angular to find count of a specific field in objects. For instance I want to find out how many ID's came in with the risk of 'Moderate', 'High','Low'?

I can count the total amount of objects for having trouble counting the number of risks associated with a type of risk like 'Moderate'

json:

[ 
{"id": 1, 
 "risk": "Moderate"
},
{"id": 2, 
 "risk": "Low"
},

{"id": 3, 
 "risk": "Moderate"
},
{"id": 4, 
 "risk": "High"
}]

component.ts

countTotalChanges() {
    let count = 0; 

        for (var i = 0; i < this.changeService.length; i++) {
            count++; 
    }
    return count;
  }

HTML

{{countTotalChanges()}}

pjlamb12 · Accepted Answer · 2019-05-17 17:54:48Z

3

If that array of objects is called items, for example, this will work:

items.filter(item => item.risk === 'Moderate').length

You can replace 'Moderate' with whichever risk type you want.

answered May 17, 2019 at 17:54

pjlamb12

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2 Comments

Rob DePietro Over a year ago

sorry for my ignorance. Where would that be implemented?

pjlamb12 Over a year ago

In whichever function you're using to count the items based on risk type. So a function could be countItemsByRiskType(riskType: string) { ... } and in that function is where you use my above answer. Then, from my original answer, replace 'Moderate' with the variable riskType. Then you can call the function and pass in the riskType you want to count.

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