Question 212317 in Javascript Question posted in
A very good W3school tutorial can be found here.

Javascript – how to build one to one relation between two array in angular

student:any=[{name:'shariful', id:'1',teacherId:'1'},{name:'Hasan', id:'2',teacherId:'2'},{name:'sohag', id:'3',teacherId:'2'}]
teacher:any=[{name:'Robi',id:'1'},{name:'Aktarujaman',id:'2'}]

needResult:any=[{name:'shariful', id:'1',teacherId:1,teacherName:'Robi'},{name:'Hasan', id:'2',teacherId:'2',teacherName:'Aktarujaman'},{name:'sohag', id:'3',teacherId:'1',teacherName:'Robi'}]

I need to join student and teacher . the output is as like as needResult .

Need to join in my angular project

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2

Answers


  1. 0

    Just map student, and add the teacherName by finding the corresponding teacher in the teacher array:

    let student =[{name:'shariful', id:'1',teacherId:'1'},{name:'Hasan', id:'2',teacherId:'2'},{name:'sohag', id:'3',teacherId:'2'}];
let teacher=[{name:'Robi',id:'1'},{name:'Aktarujaman',id:'2'}]

let result = student.map(s => {
    return {
        ...s,
        teacherName: teacher.find(t => t.id === s.teacherId).name
    }
});

console.log(result);
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  2. 0

    For linear time complexity, you can first create an object (or Map) that associates each teacher id with the teacher name. Then, you can use Array#map to create a new array where the teacher name is added to each element.

    const students = [{name:'shariful', id:'1',teacherId:'1'},{name:'Hasan', id:'2',teacherId:'2'},{name:'sohag', id:'3',teacherId:'2'}];
const teachers = [{name:'Robi',id:'1'},{name:'Aktarujaman',id:'2'}];

const teacherLookup = Object.fromEntries(teachers.map(t => [t.id, t.name]));
const res = students.map(o => ({...o, teacherName: teacherLookup[o.teacherId]}));
console.log(res);
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