jLinq is a Javascript library that lets you write queries against arrays of javascript objects and JSON data.
Syntax and Examples
Syntax for jLinq is much similar to LINQ ,
var results = jLinq.from(data.users)
.startsWith("first", "a")
.orEndsWith("y")
.orderBy("admin", "age")
.select();
Some important commands
- .startsWith( field?, value ): Check to see if the field starts with the specified value.
//Some sample queries
var results = jLinq.from(records)
.startsWith("firstname", "jo") // first name starting with 'jo'
.or("ji") // or first name starting with 'ji'
var results = jLinq.from(records)
//you can use an array of values to check
.startsWith("firstname", ["a","e","i","o","u"])
- .endsWith( field?, value ) : Check to see if the field starts with the specified value.
- .contains( field?, value ) : Check to see if the field contains the specified value.
- .match( field?, regexp ): Check to see if the
value matches the regular expression. This command will still take case
sensitivity into account.
- .empty( field? ): Check to see if the field contains any value.
- .greater( field?, value ): Check to see if the field is less than the provided value.
If the field is…
– a string, checks if it ends with the value
– an array, checks if the last element matches the value
– else, convert to a string and check returns jLinq Object
For all commands with examples see this.
Retrieve and Display Results
results[index][‘field’] will retrieve values from result object.
Following e.g. will retrieve data and displays in table,
var results = jLinq.from(data.users)
.startsWith("first", "a")
.toTable();
document.write(results);
Creating A Query Command
We can also create our own commands,
jLinq.extend({
name:"evenValues", //the name of this command i.e. method
type:"query", //the kind of command this is
count:0, //how many parameters we expect
method:function(query) {
//determine how to evaluate the value being compared
var compare = query.when({
"string":function() {
return query.value.length;
},
"array":function() {
return query.value.length;
},
"other":function() {
return query.helper.getNumericValue(query.value);
}
});
//the actual comparison
return compare % 2 == 0;
}
});
E.g using custom command,
//this method is one way to do it
jLinq.from(data.users)
.less("age", 30)
.or()
.evenValues()
.select();
When you extend a query command , several additional operator prefixed name command are added to jLinq as well. Each of these perform the correct switches when they are used.
//this orEvenValues command is generated automatically
jLinq.from(data.users)
.less("age", 30)
.orEvenValues()
.select();
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