JSON-parse-Transformed.html - JSON.parse() Value Transformed
Q
How to write a reviver function to transform values while the JSON.parse() function is parsing the JSON text string?
✍: FYIcenter.com
A
Below is a good example on using a reviver function with the JSON.parse() call
to transform parsed JSON element values:
<!-- JSON-parse-Transformed.html
Copyright (c) FYIcenter.com
-->
<html>
<body>
<script type="text/javascript">
function transformer(key, value) {
if (key == "age") {
return undefined;
} else if (key == "group" && value==null) {
return "Guest";
} else {
return value;
}
}
function parser(str) {
document.write("\njson = "+str+"\n");
var obj = JSON.parse(str,transformer);
for (var prop in obj) {
document.write(`obj.${prop} = ${obj[prop]}\n`);
}
}
document.write("<p>JSON.parse() Reviver to Transform Values:</p>");
document.write("<pre>");
parser('{"name": "Joe", "age": 25, "group": null}');
parser('{"name": "Jay", "age": 55, "group": "VIP"}');
parser('{"name": "Kim", "age": 30, "group": "Host"}');
document.write("</pre>");
</script>
</body>
</html>
The transformer() is used as the reviver function in the JSON.parse() call to remove the "age" name value pairs, and to provide a default value "Guest" to the "group" name value pairs.
Open the above code in a Web browser. You see the following output:
JSON.parse() Reviver to Transform Values:
json = {"name": "Joe", "age": 25, "group": null}
obj.name = Joe
obj.group = Guest
json = {"name": "Jay", "age": 55, "group": "VIP"}
obj.name = Jay
obj.group = VIP
json = {"name": "Kim", "age": 30, "group": "Host"}
obj.name = Kim
obj.group = Host
2017-09-08, 746👍, 0💬
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