arrays - Javascript unbind variables -


this question has answer here:

i have following code copy variable value change value.

var = [{name: 'john doe'}];  var b = a;    document.write(b[0].name + '<br />');  document.write(a[0].name + '<br /><br />');    b[0].name = 'jane doe';    document.write(b[0].name + '<br />');  document.write(a[0].name + '<br />');

but somehow change first variable value

how make variable keep value?

you assigning a-reference b. may want copying array changes a not reflected b. see this thread different assignments in javascript.

take @ fastest way duplicate array. it's speed of different array copy methods. quick answer is:

var b = a.slice();

the slice() method creates new array same elements original one. careful it's shallow copy.

you use json.stringify() , json.parse()methods doing deep copy.


-

Popular posts from this blog

Apache NiFi ExecuteScript: Groovy script to replace Json values via a mapping file -

i working apache nifi 0.5.1 on groovy script replace incoming json values ones contained in mapping file. mapping file looks (it simple .txt): header1;header2;header3 a;some text;a2 i have started following: import groovy.json.jsonbuilder import groovy.json.jsonslurper import java.nio.charset.standardcharsets def flowfile = session.get(); if (flowfile == null) { return; } flowfile = session.write(flowfile, { inputstream, outputstream -> def content = """ { "field1": "a" "field2": "a", "field3": "a" }""" def slurped = new jsonslurper().parsetext(content) def builder = new jsonbuilder(slurped) builder.content.field1 = "a" builder.content.field2 = "some text" builder.content.field3 = "a2" outputstream.write(builder.toprettystring().ge...
Read more

node.js - How do I prevent MongoDB replica set from querying the primary? -

read-operations-only: is there way have mongodb replica set, make mongodb instance on box connected to, mongodb gets queried? i have 3 ec2 instances behind aws load balancer. on each ec2 instance runs mongodb, part of replica set. i have express endpoints on nodejs , connect replica set follows mongodb.mongoclient.connect('mongodb://1.1.1.1,2.2.2.2,3.3.3.3.', function (err, db) { if (err) { complete('{}'); } else { i distribute load of queries evenly across 3 instances of mongodb replica set instead of default having queries routed ec2 instance primary mongodb defined, because destroys point of load balancer (which balance load of queries across 3 instances evenly). my understanding when connecting mongodb replica set, primary instance selected unless primary instance down, , therefore purpose of every secondary instance serve backup. in example people call hot,cold,cold. because there 2...
Read more