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AJAX is used to create more interactive applications
The following example will demonstrate how a web page can communicate with a web server while a user type characters in an input field:
Start typing a name in the input field below:
Suggestions:
First name:
In the example above, when a user types a character in the input field, a function
called showHint() is executed.
The function is triggered by the onkeyup event.
Here is the code:
<p>Start typing a name in the input field below:</p>
<p>Suggestions: <span id="txtHint"></span></p>
<form>
First name: <input type="text" onkeyup="showHint(this.value)">
</form>
<script>
function showHint(str) {
if (str.length == 0) {
document.getElementById("txtHint").innerHTML = "";
return;
} else {
const xmlhttp = new XMLHttpRequest();
xmlhttp.onload = function() {
document.getElementById("txtHint").innerHTML = this.responseText;
}
xmlhttp.open("GET", "gethint?q=" + str);
xmlhttp.send();
}
}
</script>
Code explanation:
First, check if the input field is empty (str.length == 0). If it is, clear the content of the txtHint placeholder and exit the function.
However, if the input field is not empty, do the following:
The ASP file checks an array of names, and returns the corresponding name(s) to the browser: