The simplest way to merge JSON arrays usning JQuery is to use the concat function.
var json1 = [{id: 1, name: "one"}];
var json2 = [{id: 2, name: "two"}, {id: 3, name: "three"}];
var finalObj = json1.concat(json2);
Here finalObj will contain an array of 3 objects:
[{id: 1, name: “one”},{id: 2, name: “two”}, {id: 3, name: “three”}]
JQuery Check if Element Exists using this simple piece of code. To check this in the current page, we need to check the length of the element returned by the JQuery selector, if it returns you something then the element must exists otherwise no.
if( $('#EleSelector').length ) { // use this if you are using id, replace EleSelector with the id
// it exists
}
if( $(‘.EleSelector’).length ) { // use this if you are using class, replace EleSelector with the id
// it exists
}
In case of plain javascript try this:
//you can use it for more advanced selectors
if(document.querySelectorAll("#EleSelector").length){}
if(document.querySelector("#EleSelector")){}
//you can use it if your selector has only an Id attribute
if(document.getElementById("EleSelector")){}
For a check box with the id “checkbox”, here is how to check if its checked:
$('#checkbox').is(':checked'); // Returns True if checked else False
Here is the code to remove duplicates from an Array:
var distinctVal = function(arr){
var newArray = [];
for(var i=0, j=arr.length; i<j; i++){
if(newArray.indexOf(arr[i]) == -1)
newArray.push(arr[i]);
}
return newArray;
};
To check if a variable(a) has the value null, use the following code:
if (a === null) // Best way to do it!
if (a == null) // This does return true if a is null but it returns true also if a is undefined... so avoid it
To check if a variable(a) has the value undefined, use the following code:
if (typeof a === "undefined") // This works
if (a === undefined) // This works too
if (a == undefined) // This does return true if a is undefined but it returns true also if a is null... so avoid it