How to call restful api from javascript or hit rest api URL from javascript.

What is REST api?

REST stands for Representational State Transfer. (It is sometimes spelled "ReST".) It relies on a stateless, client-server, cacheable communications protocol and in virtually all cases, the HTTP protocol is used. REST is an architecture style for designing networked applications. 

 Use following code to hit rest api url from javascript and it returns  in json format.

 var myJSONData = {"key1":"value1","key2":"value2","key3":"value3"};

    $.ajax({
            type: 'POST',
            url: 'https://example.com/ttm/subscribe-service',//rest api url
            data: myJSONData,
            dataType: 'application/json',
            success: function(data) { 
             alert("request posted to the sever successfully");
             $('#message').html('<h1>POSTED</h1>');     
          } // Success Function end
          });   // Ajax Call end

How to get meta keywords and description of a web page?

get_meta_tags() function return all meta tags of web page.
For example:
$url = "http://www.example.com";   
$tags = get_meta_tags($url);
$description     = $tags["description"];
$keywords         = $tags["keywords"];
echo 'Keywords: '.$keywords;
echo '<br/>';
echo 'Description: '.$description;

How to get title of website via website url?

The Title of website can get via site url by using file_get_contents() and php Simple html DOM parser.
php Simple html DOM parser is useful for php deveopers because php developers can easily find DOM elements of web page using php.

Getting title with file_get_contents()
<?php
function get_title($url){
  $str = file_get_contents($url);
  if(strlen($str)>0){
    $str = trim(preg_replace('/\s+/', ' ', $str));
    preg_match("/\<title\>(.*)\<\/title\>/i",$str,$title);
    return $title[1];
  }
}
//For Example:
echo get_title("http://www.example.com/");
?>

Getting title with php Simple html DOM parser
// Include the library
include('simple_html_dom.php');
/ Retrieve the DOM from a given URL
$html = file_get_html('http://www.example.com/');
// Find title tag
$titleTag        = $html->find('title',0)->innertext;
echo 'Ttile: '.$titleTag;

How can I set the heigh of the iFrame explicitly.

<p>top</p>
<p>
   <iframe id="copayCard" src="https://staging.epower.amadeus.com/Baabtravel/#Page=Flight" scrolling="no" seamless="seamless" style="border: 1px; padding: 0; overflow:hidden;"></iframe>
</p>
<p>bottom</p>
<!-- How can I set the heigh of the iFrame given its $('#eVIEW').attr('height') value?-->
/*! iFrame Resizer (iframeSizer.min.js ) - v2.7.1 - 2014-12-12
 *  Desc: Force cross domain iframes to size to content.
 *  Requires: iframeResizer.contentWindow.min.js to be loaded into the target frame.
 *  Copyright: (c) 2014 David J. Bradshaw - dave@bradshaw.net
 *  License: MIT
 */
 !function(){"use strict";function a(a,b,c){"addEventListener"in window?a.addEventListener(b,c,!1):"attachEvent"in window&&a.attachEvent("on"+b,c)}function b(){var a,b=["moz","webkit","o","ms"];for(a=0;a<b.length&&!w;a+=1)w=window[b[a]+"RequestAnimationFrame"];w||c(" RequestAnimationFrame not supported")}function c(a){y.log&&"object"==typeof console&&console.log(s+"[Host page"+u+"]"+a)}function d(a){function b(){function a(){h(B),f(),y.resizedCallback(B)}k("Height"),k("Width"),i(a,B,"resetPage")}function d(a){var b=a.id;c(" Removing iFrame: "+b),a.parentNode.removeChild(a),y.closedCallback(b),c(" --")}function j(){var a=A.substr(t).split(":");return{iframe:document.getElementById(a[0]),id:a[0],height:a[1],width:a[2],type:a[3]}}function k(a){var b=Number(y["max"+a]),d=Number(y["min"+a]),e=a.toLowerCase(),f=Number(B[e]);if(d>b)throw new Error("Value for min"+a+" can not be greater than max"+a);c(" Checking "+e+" is in range "+d+"-"+b),d>f&&(f=d,c(" Set "+e+" to min value")),f>b&&(f=b,c(" Set "+e+" to max value")),B[e]=""+f}function l(){var b=a.origin,d=B.iframe.src.split("/").slice(0,3).join("/");if(y.checkOrigin&&(c(" Checking connection is from: "+d),""+b!="null"&&b!==d))throw new Error("Unexpected message received from: "+b+" for "+B.iframe.id+". Message was: "+a.data+". This error can be disabled by adding the checkOrigin: false option.");return!0}function m(){return s===(""+A).substr(0,t)}function n(){var a=B.type in{"true":1,"false":1};return a&&c(" Ignoring init message from meta parent page"),a}function o(){var a=A.substr(A.indexOf(":")+r+6);c(" MessageCallback passed: {iframe: "+B.iframe.id+", message: "+a+"}"),y.messageCallback({iframe:B.iframe,message:JSON.parse(a)}),c(" --")}function q(){if(null===B.iframe)throw new Error("iFrame ("+B.id+") does not exist on "+u);return!0}function w(){var a=B.iframe.getBoundingClientRect();return e(),{x:Number(a.left)+Number(v.x),y:Number(a.top)+Number(v.y)}}function x(a){var b=a?w():{x:0,y:0};c(" Reposition requested from iFrame (offset x:"+b.x+" y:"+b.y+")"),v={x:Number(B.width)+b.x,y:Number(B.height)+b.y},f()}function z(){switch(B.type){case"close":d(B.iframe),y.resizedCallback(B);break;case"message":o();break;case"scrollTo":x(!1);break;case"scrollToOffset":x(!0);break;case"reset":g(B);break;case"init":b(),y.initCallback(B.iframe);break;default:b()}}var A=a.data,B={};m()&&(c(" Received: "+A),B=j(),!n()&&q()&&l()&&(z(),p=!1))}function e(){null===v&&(v={x:void 0!==window.pageXOffset?window.pageXOffset:document.documentElement.scrollLeft,y:void 0!==window.pageYOffset?window.pageYOffset:document.documentElement.scrollTop},c(" Get position: "+v.x+","+v.y))}function f(){null!==v&&(window.scrollTo(v.x,v.y),c(" Set position: "+v.x+","+v.y),v=null)}function g(a){function b(){h(a),j("reset","reset",a.iframe)}c(" Size reset requested by "+("init"===a.type?"host page":"iFrame")),e(),i(b,a,"init")}function h(a){function b(b){a.iframe.style[b]=a[b]+"px",c(" IFrame ("+a.iframe.id+") "+b+" set to "+a[b]+"px")}y.sizeHeight&&b("height"),y.sizeWidth&&b("width")}function i(a,b,d){d!==b.type&&w?(c(" Requesting animation frame"),w(a)):a()}function j(a,b,d){c("["+a+"] Sending msg to iframe ("+b+")"),d.contentWindow.postMessage(s+b,"*")}function k(){function b(){function a(a){1/0!==y[a]&&0!==y[a]&&(k.style[a]=y[a]+"px",c(" Set "+a+" = "+y[a]+"px"))}a("maxHeight"),a("minHeight"),a("maxWidth"),a("minWidth")}function d(a){return""===a&&(k.id=a="iFrameResizer"+o++,c(" Added missing iframe ID: "+a+" ("+k.src+")")),a}function e(){c(" IFrame scrolling "+(y.scrolling?"enabled":"disabled")+" for "+l),k.style.overflow=!1===y.scrolling?"hidden":"auto",k.scrolling=!1===y.scrolling?"no":"yes"}function f(){("number"==typeof y.bodyMargin||"0"===y.bodyMargin)&&(y.bodyMarginV1=y.bodyMargin,y.bodyMargin=""+y.bodyMargin+"px")}function h(){return l+":"+y.bodyMarginV1+":"+y.sizeWidth+":"+y.log+":"+y.interval+":"+y.enablePublicMethods+":"+y.autoResize+":"+y.bodyMargin+":"+y.heightCalculationMethod+":"+y.bodyBackground+":"+y.bodyPadding+":"+y.tolerance}function i(b){a(k,"load",function(){var a=p;j("iFrame.onload",b,k),!a&&y.heightCalculationMethod in x&&g({iframe:k,height:0,width:0,type:"init"})}),j("init",b,k)}var k=this,l=d(k.id);e(),b(),f(),i(h())}function l(a){if("object"!=typeof a)throw new TypeError("Options is not an object.")}function m(){function a(a){if("IFRAME"!==a.tagName.toUpperCase())throw new TypeError("Expected <IFRAME> tag, found <"+a.tagName+">.");k.call(a)}function b(a){a=a||{},l(a);for(var b in z)z.hasOwnProperty(b)&&(y[b]=a.hasOwnProperty(b)?a[b]:z[b])}return function(c,d){b(c),Array.prototype.forEach.call(document.querySelectorAll(d||"iframe"),a)}}function n(a){a.fn.iFrameResize=function(b){return b=b||{},l(b),y=a.extend({},z,b),this.filter("iframe").each(k).end()}}var o=0,p=!0,q="message",r=q.length,s="[iFrameSizer]",t=s.length,u="",v=null,w=window.requestAnimationFrame,x={max:1,scroll:1,bodyScroll:1,documentElementScroll:1},y={},z={autoResize:!0,bodyBackground:null,bodyMargin:null,bodyMarginV1:8,bodyPadding:null,checkOrigin:!0,enablePublicMethods:!1,heightCalculationMethod:"offset",interval:32,log:!1,maxHeight:1/0,maxWidth:1/0,minHeight:0,minWidth:0,scrolling:!1,sizeHeight:!0,sizeWidth:!1,tolerance:0,closedCallback:function(){},initCallback:function(){},messageCallback:function(){},resizedCallback:function(){}};b(),a(window,"message",d),window.jQuery&&n(jQuery),"function"==typeof define&&define.amd?define([],m):"object"==typeof exports?module.exports=m():window.iFrameResize=m()}();
//# sourceMappingURL=iframeResizer.map

$(function() {
  var $iFrame = $('#copayCard');
  // For full API see https://github.com/davidjbradshaw/iframe-resizer
  $iFrame.iFrameResize({
    log: true,
    checkOrigin: true, // allow cross-site scripting
    sizeHeight: true,
    sizeWidth: false,
    autoResize: true,
    //enablePublicMethods: true,
  //  heightCalculationMethod: 'bodyScroll'
  });
});