Retrieve site collection quota and used storage from REST or JSOM

Question

Is there a way to retrieve the amount of storage used and the quota limit for the Site Collection using the JSOM client or the REST web services?

Answer 1

The REST query

https://<siteUrl>/_api/site/usage

will return the following:

{
    "d": {
        "Usage": {
            "__metadata": {
                "type": "SP.UsageInfo"
            },
            "Bandwidth": "0",
            "DiscussionStorage": "0",
            "Hits": "0",
            "Storage": "354721461",
            "StoragePercentageUsed": 0.0330360104329884,
            "Visits": "0"
        }
    }
}

Storage will give us "Storage Used"(in Bytes) not the "Total Storage" you can calculate the amount of storage used based on Storage and StoragePercentageUsed

Answer 2

How to access information about site collection usage via CSOM

SP.UsageInfo object provides fields that are used to access information about site collection usage.

var context = new SP.ClientContext.get_current();
var site = context.get_site();
context.load(site,'Usage');  
context.executeQueryAsync(
    function() {

        var siteUsageInfo = site.get_usage();                   
        console.log(siteUsageInfo.get_storage());          
        console.log(siteUsageInfo.get_storagePercentageUsed());             
    },
    function(sender,args){
       console.log(args.get_message());
    }
);