JavaScript Promise.all() Tutorials in Hindi

What is Promise all ?

Promise.all () एक ऐसा method है जिसके द्वारा same type के multiple promise को cheack करके resolve() या reject() method की value को access किया जाता है |

Syntax for create "promise" :

Promise.all([promise_name_1, promise_name_2,…. promise_name_n,]).then((any_para_meter)=>{
//Here return resolve value like console.log()
}).catch((any_para_meter)=>{
//Here return resolve value like console.log()
})
})

Example of promise.all


<script>     
let emp1 = new Promise((resolve, reject)=>{
      setTimeout(()=>{
        let dtls ={
          id : 1,
          name : "Ramesh Kumar",
          salary : 5000
        }
        console.log("first data has send");
        resolve(dtls)

      }, 1000*1)
    })

    let emp2 = new Promise((resolve, reject)=>{
      setTimeout(()=>{
        let dtls ={
          id : 2,
          name : "Suresh Kumar",
          salary : 7000
        }
        console.log("Second data has send");
        resolve(dtls)

      }, 1000*2)
    })

    let emp3 = new Promise((resolve, reject)=>{
      setTimeout(()=>{
        let dtls ={
          id : 3,
          name : "Ganesh Kumar",
          salary : 12000
        }
        console.log("Third data has send");
        resolve(dtls)

      }, 1000*2)
    })


    Promise.all([emp1, emp2, emp3]).then((x)=>{
      let total = 0;
      setTimeout(()=>{
        //console.log(x)

        x.forEach((a)=>{
          total += a.salary
          console.log(`Employ id = ${a.id}, Employ Name = ${a.name}, Employ Salary = ${a.salary},`)
        })
        console.log(`Total Amount on Salary : ${total}` )
      },1000)
    }).catch((y)=>{
      console.log(y)
    })
</script>