How to convert JSON to array and loop over it in jQuery?

Question

I am using JSON to communicate with the user. PHP converts array to JSON to this form:

{"success":"text-to-display","warning":"NONE","notice":"text-to-display","error":"NONE"}

jQuery display notification:

function callback (data){
    if(data.notice !== 'NONE'){
        displayNotice(data.notice);
    }
    if(data.success !== 'NONE'){
        displaySuccess(data.success);
    }
    if(data.warning !== 'NONE'){
        displayWarning(data.warning);
    }
    if(data.error !== 'NONE'){
        displayError(data.error);
    }
}

Unfortunately, in this method can't display two error or two notice or two warning, because new statement replace old statement.

<?php
$uwaga['error'] = 'old statement';
$uwaga['error'] = 'new statement';
// display only "new statement"
echo json_encode($uwaga);
?>

I think that use array:

<?php
$uwaga = array();
$uwaga[1] = array('type' => 'notice', 'text' => 'old statement');
$uwaga[2] = array('type' => 'notice', 'text' => 'new statement');
// display "new statement" and "old statement"
// generate: {"1":{"type":"notice","text":"old statement"},"2": {"type":"notice","text":"new statement"}}
    echo json_encode($uwaga);
?>

How "translate" this PHP code on jQuery (mainly: how convert json object to array? how loop use? how using this loop? How refer to $uwaga[$key]['name'] and $uwaga[$key]['text'])?

foreach ($uwaga as $key => $value) {
switch ($uwaga[$key]['name']) {
    case 'warning':
        displayWarning($uwaga[$key]['text']);
        break;
}}

This is a great question - lots of detail, and prior effort. Hope to see you asking more (and maybe answering too!) in the future. +1 — halfer
– halfer, Commented Jul 6, 2014 at 9:39

Rob Schmuecker · Accepted Answer · 2014-07-06 09:25:46Z

OK let's say we have a PHP array

PHP:

<?php
$myArray = array(
    "test1"=>array("name"=>"test1name", "value"=>"test1value"),
    "test2"=>array("name"=>"test2name", "value"=>"test2value"),
    "test3"=>array("name"=>"test3name", "value"=>"test3value")
);

// Now make a javascript variable containing echoed JSON
echo "<script type='text/javascript'>var returnedJSON = " . json_encode($myArray) . ";</script>";

This will output the below JSON giving you a javascript object:

var returnedJSON = {"test1":{"name":"test1name","value":"test1value"},"test2":{"name":"test2name","value":"test2value"},"test3":{"name":"test3name","value":"test3value"}};

Javascript:

//Once you have the variable from above which can come in various ways (through ajax, jsonp etc) you can iterate over it quite simply in jQuery
$.each(returnedJSON, function (index, value) {
    console.log(index + ": " + value.name);
});

http://api.jquery.com/jquery.each/

Demo http://jsfiddle.net/robschmuecker/HqarE/1/

halfer · Accepted Answer · 2014-07-06 09:33:32Z

Rather than this:

$uwaga = array();
$uwaga[1] = array('type' => 'notice', 'text' => 'old statement');
$uwaga[2] = array('type' => 'notice', 'text' => 'new statement');

Just do this, without indices:

$uwaga = array();
$uwaga[] = array('type' => 'notice', 'text' => 'old statement');
$uwaga[] = array('type' => 'notice', 'text' => 'new statement');

That will assign them indices (from zero, not one) at the end of the array.

Then take all of these:

if(data.notice !== 'NONE'){
    displayNotice(data.notice);
}
if(data.success !== 'NONE'){
    displaySuccess(data.success);
}
if(data.warning !== 'NONE'){
    displayWarning(data.warning);
}
if(data.error !== 'NONE'){
    displayError(data.error);
}

... and wrap them in a block of jQuery's each() as Rob recommends. It will then become (assuming the data is in json.messages):

$.each(json.messages, function (index, data) {
    if(data.notice !== 'NONE'){
        displayNotice(data.notice);
    }
    if(data.success !== 'NONE'){
        displaySuccess(data.success);
    }
    if(data.warning !== 'NONE'){
        displayWarning(data.warning);
    }
    if(data.error !== 'NONE'){
        displayError(data.error);
    }
});

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