Find string via regex in JavaScript

Question

I'm getting the following response from ajax GET request ( using $.Ajax )

<div class="clienthoverpage_content">
    <div class="school_info" id="lesson_51123">
        <div class="_desc_content" id="lesson_content">
            <div class="_desc_icon">
            </div>
            <div class="_desc_description">
                <h1 class="hover_name" id="lesson_name"></h1>
                <div class="fraud_warning" id="lesson_fraud_warnings"></div>
                <div class="_desc_class_info" id="lesson_class_info">
                    <div id="lesson_class_name" class="ellipsis"></div>
                    <div id="lesson_type" class=""></div>
                </div>
                <div class="_desc_descriptors" id="lesson_descriptors">
                </div>
                                                    </div>
        </div>
    </div>
</div>
<script type="text/javascript">

    fnInitDisplay = function() {
        UserYou.LoadContexts( g_rgAppContextData );
        BuildHover( 'lesson_51123',  {"id":"123441","class":"51112","student":"506854340"} );
        $('lesson_51123').show();
    }

</script>

The line I am interested in is

BuildHover( 'lesson_51123', {"id":"123441","class":"51112","student":"506854340"} );

I want to take the values of id , class , student . I'm assuming the best way doing this would be using regex but I am failing to find the right regex.

Answer 1

I'm not so great at Regex so I'll give you my example where I just use the indexOf and substring methods. JS-FIDDLE

var str = 'UserYou.LoadContexts( g_rgAppContextData );'+
'BuildHover( "lesson_51123",  {"id":"123441","class":"51112","student":"506854340"} );'+
    '$("lesson_51123").show();';

var _id = '"id":"';
var _class = '","class":"';
var _student = '","student":"';

var classIndex = str.indexOf(_class);
var idIndex = str.indexOf(_id);
var studentIndex = str.indexOf(_student);
var endStr = str.indexOf('"}');

var resultID = str.substr(idIndex + _id.length, classIndex - (idIndex + _id.length) );
var resultClass = str.substr(classIndex + _class.length, studentIndex - (classIndex + _class.length));
var resultStudent = str.substr(studentIndex + _student.length, str.length-2 - (studentIndex + _student.length));

Answer 2

var a = str.match(/BuildHover\(\s*'.*?',\s*(.*?)\s*\)/);
// Note a[1] will be a string use JSON.parse(a[1]) to get an object
console.log(a[1]); // {"id":"123441","class":"51112","student":"506854340"}

Breakdown:

/ # start regex
  BuildHover\( # "BuildHover("
  \s* # 0 or more spaces
  ' # single quote ("'")
  .*?  # everything non gready
  ', # Match "',"
  \s* # 0 or more spacres
  ( # start capture group
    .*? # everything non gready
  ) # end group
  \s* # 0 or more spaces
  \) # ")"
/ # end regex

Answer 3

var string = 'UserYou.LoadContexts( g_rgAppContextData );'+
'BuildHover( "lesson_51123",  {"id":"123441","class":"51112","student":"506854340"} );'+
    '$("lesson_51123").show();';

var jsonString = string.match(/\{"id":.*?\}/);
var jsonObject = JSON.parse(jsonString);

console.log(jsonObject.id);
console.log(jsonObject.class);
console.log(jsonObject.student);

You can find the String in your result and then use JSON.parse to get an object. Even though it's not really clean to do stuff like that.