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Type Checks String: typeof object === "string" Number: typeof object === "number" Boolean: typeof object === "boolean" Object: typeof object === "object" Plain Object: jQuery.isPlainObject( object ) Function: jQuery.isFunction( object ) Array: jQuery.isArray( object ) Element: object.nodeType null: object === null null or undefined: object == null undefined: Global Variables: typeof variable === "undefined" Local Variables: variable === undefined Properties: object.prop === undefined

It is very easy to define custom validator in jQuery validation plugin. For example, you have a form that contains two text input fields, you want to limit these two text input only accept a number ranging from 0 to 1000. Here is what you do: 1. Create a HTML markup. Note the input type is number, which will only accept number. You have to define the name attribute, this name will be referenced in step 3.         2. Define the custom validation method:             jQuery.validator.addMethod('range', function (value, element, param) {                 return this.optional(element) || (value >= param[0] && value <= param[1]);             }, 'Please enter a range between 0 to 1000 !'); 3. Apply custom validation       ...