Delay each loop iteration in node js, async

Question

I have the code below:

var request = require(\'request\');
var cheerio = require (\"cheerio\");
var async= require(\"async\");

var MyLink=\"www.mylink.com\"         


        

Answer 1

Since you're already using async, async.wilst would do nicely as a replacement for for.

whilst is an asynchronous while-like function. Each iteration is only run after the previous iteration has called its completion callback. In this case, we can simply postpone execution of the completion callback by 10 seconds with setTimeout.

var i = 0;
async.whilst(
    // test to perform next iteration
    function() { return i <= TheUrl.length-1; },

    // iterated function
    // call `innerCallback` when the iteration is done
    function(innerCallback) {
        var url = 'www.myurl.com='+TheUrl[i];
        request(url, function(error, resp, body) { 
            if (error) return innerCallback(error); 
            var $ = cheerio.load(body);
            //Some calculations again...

            // wait 10 secs to run the next iteration
            setTimeout(function() { i++; innerCallback(); }, 10000);
        });
    },

    // when all iterations are done, call `callback`
    callback
);