Check whether the list exists or not using ECMAScript

In SharePoint 2013 when you create any SharePoint Hosted App it will create separate web for the app you created. You can find it easily by verifying the URL at the browser.
1) SPHostUrl 2) SPAppWebUrl

Get Host Web Url in SharePoint 2013/Office365 apps using JSOM

Get HostWeb URL through JavaScript object model:

Just do copy/paste the below code and execute it.

Note: The below shared code is 100% verified/executed.

Please reach the below post URL to get the hostweb url through REST service

http://sharepointquicksolutions.blogspot.com/2016/12/get-sharepoint-host-web-url-using-rest.html 


Appmanifest.xml:
Set read level permisisons to the web

Default.aspx:

<p id="getHostWebURL"> </p>

App.js

'use strict';
var hostweburl, appweburl;
var website;

$(document).ready(function () {
    appweburl = window.location.protocol + "//" + window.location.host + _spPageContextInfo.webServerRelativeUrl;
    hostweburl = _spPageContextInfo.siteAbsoluteUrl;

    //hostweburl = decodeURIComponent(getQueryStringParameter("SPHostUrl"));
    //appweburl = decodeURIComponent(getQueryStringParameter("SPAppWebUrl"));
    var scriptbase = hostweburl + "/_layouts/15/";

    $.getScript(scriptbase + "SP.Runtime.js",
        function () {
            $.getScript(scriptbase + "SP.js", retrieveListItems);
        }
    );
});

// Function to retrieve a query string value.
// For production purposes you may want to use
// a library to handle the query string.
function getQueryStringParameter(paramToRetrieve) {
    var params =
        document.URL.split("?")[1].split("&");
    var strParams = "";
    for (var i = 0; i < params.length; i = i + 1) {
        var singleParam = params[i].split("=");
        if (singleParam[0] == paramToRetrieve)
            return singleParam[1];
    }
}

function retrieveListItems() {
    var context = new SP.ClientContext(appweburl);
    var appContextSite = new SP.AppContextSite(context, hostweburl);
    website = appContextSite.get_web();
    context.load(website);
    context.executeQueryAsync(onGetWebSuccess, onGetWebFail);

    //the remaining code is omitted for clarity  
}

function onGetWebSuccess() {
    alert("calling" + website.get_title());
    $('#getHostWebURL').text("The title of the host web of this app is " + website.get_title());
}

function onGetWebFail(sender, args) {
    alert('Failed to get lists. Error:' + args.get_message());
}

How to: Create fields in sharepoint list using ECMAScript

By using below code we can create fields of different types using ECMAScript:

function createFields()
{
   currentcontext = new SP.ClientContext.get_current();
   web = clientContext.get_web();
   this.list = web.get_lists().getByTitle(‘ListName’);  
 //Add new fields to the list

//Single line of text Field
this.newColumn = oList.get_fields().addFieldAsXml("", true,
    SP.AddFieldOptions.defaultValue);
 
//Multi line of text Field
this.newColumn = oList.get_fields().addFieldAsXml("", true,
    SP.AddFieldOptions.defaultValue);
 
//Boolean Field
this.newColumn = oList.get_fields().addFieldAsXml("", true,
    SP.AddFieldOptions.defaultValue);

//Number Field
this.newColumn = oList.get_fields().addFieldAsXml("", true,
    SP.AddFieldOptions.defaultValue);

//DateTime Field
this.newColumn = oList.get_fields().addFieldAsXml("", true,
  SP.AddFieldOptions.defaultValue);

//People Picker Field
this.newColumn = oList.get_fields().addFieldAsXml("", true,
  SP.AddFieldOptions.defaultValue);

//Choice field(dropdown)
 this.newColumn= oList.get_fields().addFieldAsXml("ChoiceAChoiceAChoiceBChoiceCChoiceD", true, 
  SP.AddFieldOptions.defaultValue);
 
 currentcontext.load(this.newfield);
 currentcontext.executeQueryAsync(Function.createDelegate(this, this.onListCreateSuccess), Function.createDelegate(this, this.onQueryFailed));
}

function onListCreateSuccess(sender, args) {alert('sucess');
    alert("Field Name: " + this.newfield.get_title());
}
 
function onQueryFailed(sender, args) {
 alert('request failed ' + args.get_message() + '\n' + args.get_stackTrace());
}

Note: SP.Field.typeAsString Property is used to Gets or sets a value that specifies the type of the field.[From Msdn:http://msdn.microsoft.com/en-us/library/ee553500.aspx]

SharePoint Interview Questions and Answers: List vs Library

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1.  Difference between list and library?
2.  New features introduced in sp2010 on Lists and Libraries compared to SP2007?
3. List throttling?
4. External List throttling?
5. Column level validations?

Error occurred in deployment step 'Uninstall app for SharePoint":

I am facing the below issues regularly while deploying the SharePoint hosted apps to both either office 365 sites or SharePoint sites from the visual studio. So guys, please help me on it.

 Error occurred in deployment step 'Uninstall app for SharePoint': Only users who can View Pages can list Apps.
Error occurred in deployment step 'Uninstall app for SharePoint': The underlying connection was closed: An unexpected error occurred on a receive.
Error occurred in deployment step 'Uninstall app for SharePoint': The underlying connection was closed: A connection that was expected to be kept alive was closed by the server.
Error occurred in deployment step 'Uninstall app for SharePoint': Communication with the SharePoint server is canceled.