var my_callback = function (response) {
  var msg = "Got back "+response;
  alert(msg);                  
};
jQuery.ajax("hello.txt",   // URL
  {                        // options
    success: my_callback   // callback
  }
);

jQuery.ajax("hello.txt", // URL
  {                      // options
    success:             // callback
      // describe an anonymous function
      function(reply) {    
        var msg = "Got back " + reply;
        alert(msg);                  
    }
  }
);

// call 'action', a function, 
// on every element of 'list'
forAll = function(list, action) { 
  for (var i=0; i<list.length; i++)
    action(list[i]);
}

// alert twice
forAll(['x', 'y'], alert);

// log three times
forAll([12, 345, 6],
  function(v) {console.log(v);});

• Takes one GET argument, line
• Returns the line of song at that position
• lyrics.php?line=1
• lyrics.php?line=5

• Add data to array of options
• e.g. data : {line: 5}

>

// counter value, initially zero
counter = 0; 

// clicking either button does this:
add = function(changeAmount) {
  counter = counter + changeAmount;
  
  // update number
  counterLabel.innerHTML = counter; 
  
  // get line from server
  jQuery.ajax("lyrics.php",
  { // use two options
    data: {line: counter}, // to GET
    success: function (reply) { 
      // update display!
      resultLabel.innerText = reply; 
    }
  });
};

$("button").each(function(){
   this.disabled = true; // or false
}); 
$("#spinnerImg").show(); // or hide
<img id="spinnerImg" src="spinner.gif" hidden="true">

// ask jQuery to run function
// once page is loaded
jQuery(function() {
   counter = 1;
   add(0); //refresh, don't change value
});

• Takes one GET argument, an integer guess between 1 and 10
• Returns You Win! or Guess Again.
• E.g.: guess 4
• Task: write code to guess hidden number
// here's code to make one guess: var g=4; jQuery.ajax("mystery.php", { data: {guess: g}, // to GET success: function (reply) { alert([g, reply]); console.log([g, reply]); } }); // how to make 10 guesses?
• Hint (click to show)