add filters to scan dynamodb node js\ code example

Example 1: aws lambda dynamodb nodejs scan

export const scanTable = async (tableName) => {
    const params = {
        TableName: tableName,
    };

    let scanResults = [];
    let items;
    do{
        items =  await documentClient.scan(params).promise();
        items.Items.forEach((item) => scanResults.push(item));
        params.ExclusiveStartKey  = items.LastEvaluatedKey;
    }while(typeof items.LastEvaluatedKey != "undefined");

    return scanResults;

};

Example 2: dynamodb get all items nodejs

var docClient = new AWS.DynamoDB.DocumentClient();

var params = {
    TableName: "users",
    FilterExpression: "#user_status = :user_status_val",
    ExpressionAttributeNames: {
        "#user_status": "user_status",
    },
    ExpressionAttributeValues: { ":user_status_val": 'somestatus' }

};

docClient.scan(params, onScan);
var count = 0;

function onScan(err, data) {
    if (err) {
        console.error("Unable to scan the table. Error JSON:", JSON.stringify(err, null, 2));
    } else {        
        console.log("Scan succeeded.");
        data.Items.forEach(function(itemdata) {
           console.log("Item :", ++count,JSON.stringify(itemdata));
        });

        // continue scanning if we have more items
        if (typeof data.LastEvaluatedKey != "undefined") {
            console.log("Scanning for more...");
            params.ExclusiveStartKey = data.LastEvaluatedKey;
            docClient.scan(params, onScan);
        }
    }
}