Move object from one array to another

问题

i have one object that one of the properties is an array of objects, the idea is to move objects from that array to no new one if one condition is true.

public $onInit(): void {
  this.getTicket();
}

public ticket: any; // Object with the array
public comments: any = []; // New array to move the elements
public getTicket(): void {
    this.ticketService
        .getTicketComplete(this.$stateParams.ticketID)
        .then((response: any) => {
            this.ticket = response;
            this.stringToDate(this.ticket);
            this.ticket.messages.forEach((elem, index) => {
                if (elem.type === "comment") {
                    this.ticket.messages.splice(index, 1);
                    this.comments.push(elem);
                }
            });
            console.log(this.ticket);
    });
}

the problem that i have is the next one: the array has to types of objects, messages and comments, if the array has 2 messages and 3 comments it should push to the new array 3 comments and leave 2 messages, but is moving only 2 comments.

Any idea. Thanks for your help.

回答1:

This is the way You do it:

var array1 = [1, 2, 3, 4, 5];
var array2 = [];

array1.forEach(function(elem, index) {
  array1.splice(index, 1);
  array2.push(elem);
});

console.log(array1); //[2, 4]
console.log(array2); //[1, 3, 5]

This is an example of how it can be done:

var array1 = [1, 2, 3, 4, 5];
var array2 = [];

for(var i = 0; i < array1.length; i++) {
  array2.push(array1[i]);
  array1.splice(i, 1);
  i--; //decrement i IF we remove an item
}

console.log(array1); //[]
console.log(array2); //[1, 2, 3, 4, 5]

Specific use-case for you:

let messages = this.ticket.messages;
for(let i = 0; i < messages.length; i++) {
  let message = messages[i];
  if (message.type === "comment") {
    this.comments.push(message);
    messages.splice(i, 1);
    i--;
  }
}

回答2:

You are removing elements as you loop through your array - this is never a good idea. A better way to solve this issue is to add them to this.comments first and when the foreach is finalized, start looping over this.comments and remove those that are in this array out of the messages.

回答3:

Here we go the async way baby:

var array1 = [1, 2, 3, 4, 5];
var array2 = [];

async function fillArray() {
  array1.forEach(function(elem, index) {
    console.log("elem: ", elem)
    array2.push(elem); 
  })
}

async function emptyArray(){
  fillArray().then(() =>{
    array1.length = 0; 
 })
}

emptyArray().then(() => { 
  console.log("array1: ", array1); //[]
  console.log("array2: ", array2); //[1, 2, 3, 4, 5]
})

An another great move, conditional way, cheer:

var array1 = [1, 2, 3, 4, 5];
var array1Length= array1.length;
var array2 = [];
 
  array1.forEach((elem, index) => {
    array2.push(elem); 
    if(array2.length === array1Length) array1.length=0
  })
  
  console.log("array1: ", array1); //[]
  console.log("array2: ", array2); //[1, 2, 3, 4, 5]

来源：https://stackoverflow.com/questions/45919837/move-object-from-one-array-to-another

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