Unable to run jsvascript until page refresh - php

Question

I've started using ajax requests recently. I am making a mobile web application where I am to the request for data on PHP side server script. The javascript function is to automatically execute when the user navigates to the page. But the script seems not to run until I refresh the page, here is my javascript code.
<script>
$( document ).ready(function(){
Date.prototype.yyyymmdd = function() {
var yyyy = this.getFullYear().toString();
var mm = (this.getMonth()+1).toString();
var dd = this.getDate().toString();
return yyyy + '-' + (mm[1]?mm:"0"+mm[0]) + '-' + (dd[1]?dd:"0"+dd[0]);
};
function requestContent() {
var date = new Date();
$.ajax({
type:'POST',
url:'php/app/adminTimeline.php',
data:{
date: date.yyyymmdd()
},
success: function(data) {
if (data == '') {
alert("No data found!");
} else {
// $("#loading_spinner").css({"display":"none"});
$('#timeline-content').prepend(data);
}
},
error: function(data) {
// $("#loading_spinner").css({"display":"none"});
alert("Something went Wrong!");
}
});
}
window.onload = requestContent();
});
</script>
The document.onready method and window.onload the method seems not to be working too.
Ps: I have the Jquery library linked in the header too.

Answer 1

Code included inside $( document ).ready() will only run once the page Document Object Model (DOM) is ready for JavaScript code to execute.
https://learn.jquery.com/using-jquery-core/document-ready/
Also you're calling requestContent()
window.onload must be function, not returning value.
$(document).ready(function(){
// here you ajax
}
https://jsfiddle.net/cqfq5on5/1/

Answer 2

The code window.onload=requestContent(); will execute when the window loads, not necessarily when the entire document has loaded.
However where you create the date object, uses this, which executes after the document is fully loaded
$(document).ready(function(){
//Code
});
This means, that the POST request will be made once the window loads, which is before the document is fully loaded, thus, that date object will not exist until the page is refreshed, at which point the Javascript was likely cached. Also another answer (#sagid) pointed out, window.onload cannot be a returning value but must be a function.
i.e.
window.onload=function(){
//Code
};
This means, your solution is to change window.onload=requestContent(); to
$(document).ready(function(){
requestContent();
});
Good luck!