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    set

    Summary

    Binds an object property to a function to be called when there is an attempt to set that property.

    Syntax

    {set prop(val) { . . . }}

    Parameters

    prop
    the name of the property to bind to the given function
    val
    an alias for the variable that holds the value attempted to be assigned to prop

    Description

    In JavaScript, a setter can be used to execute a function whenever a specified property is attempted to be changed. Setters are most often used in conjunction with getters to create a type of pseudo-property. It is not possible to simultaneously have a setter on a property that holds an actual value.

    JavaScript 1.8.1 note

    Starting in JavaScript 1.8.1, setters are no longer called when setting properties in object and array initializers.

    JavaScript 1.8.5 note

    Starting in JavaScript 1.8.5, set operator:

    A setter can be removed using the delete operator.

    Examples

    Defining a setter with the set operator

    This will define a pseudo-property current of object o that, when assigned a value, will update log with that value:

    var o = {
      set current (str) {
        return this.log[this.log.length] = str;
      },
      log: []
    }
    

    Note that current is not defined and any attempts to access it will result in undefined

    Removing a setter with the delete operator

    delete o.current;
    

    Browser compatibility

    Based on Robert Nyman's page

    No support (notably in IE6-8) means that the script will trigger a syntax error.

    Feature Firefox (Gecko) Chrome Internet Explorer Opera Safari
    Basic support 2.0 (1.8.1) 1 9 9.5 3
    Feature Firefox Mobile (Gecko) Android IE Mobile Opera Mobile Safari Mobile
    Basic support ? ? ? ? ?

     

    Document Tags and Contributors

    Contributors to this page: Sevenspade
    Last updated by: Sevenspade,