How to inject javascript in SharePoint Online with powershell

Hi All,

As we know that SharePoint Online recommended not to update master pages.
If we want to add/update master page we have to use inject JavaScript to any Site or Site Collection via a User Custom Action's ScriptLink property.

we can add user custom actions in different ways.

I. Using PowerShell:

i. Upload the files, like JQuery, custom javascript and css files.
ii. Now open powershell and connect to SharePoint online as below.

$urlAdmin = https://YOUR.TENANT-admin.sharepoint.com
$user = "administrator@YOUR.TENANT.onmicrosoft.com"
$password = "YOUR.TENANT.PASSWORD"
$urlSite = https://YOUR.TENANT.sharepoint.com/sites/TestSiteCollection

$passwordSecureString = ConvertTo-SecureString -string $password -AsPlainText -Force
$credential = New-Object -TypeName System.Management.Automation.PSCredential -argumentlist $user, $passwordSecureString

Connect-SPOService -Url $urlAdmin -Credential $credential

$spoCredentials = New-Object -TypeName Microsoft.SharePoint.Client.SharePointOnlineCredentials -argumentlist $user, $passwordSecureString

iii. Now add custom actions as below

#Injecting JQuery file
$spoCtx = New-Object Microsoft.SharePoint.Client.ClientContext($urlSite)
$spoCtx.Credentials = $spoCredentials
$spoCtx.RequestTimeout = "500000"
$newAction = $spoCtx.Site.UserCustomActions.Add();
$newAction.Location = "ScriptLink";
$newAction.scriptSrc = "~SiteCollection/SiteAssets/scripts/jquery-2.1.3.min.js";
$newAction.Sequence = 1001;
$newAction.Update();
$spoCtx.ExecuteQuery();

#Injecting custom javascript file
$newAction = $spoCtx.Site.UserCustomActions.Add();
$newAction.Location = "ScriptLink";
$newAction.scriptSrc = "~SiteCollection/SiteAssets/scripts/CustomJS.js";
$newAction.Sequence = 1002;
$newAction.Update();
$spoCtx.ExecuteQuery();

Thats it now you can add other javascript/css files from CustomJS.js files.

Its so simple right!!!

Here the complete code.