Ext JS 4.0.7 Sencha Docs

Boolean

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The Boolean object is an object wrapper for a boolean value.

The value passed as the first parameter is converted to a boolean value, if necessary. If value is omitted or is 0, -0, null, false, NaN, undefined, or the empty string (""), the object has an initial value of false. All other values, including any object or the string "false", create an object with an initial value of true.

Do not confuse the primitive Boolean values true and false with the true and false values of the Boolean object.

Any object whose value is not undefined or null, including a Boolean object whose value is false, evaluates to true when passed to a conditional statement. For example, the condition in the following if statement evaluates to true:

x = new Boolean(false);
if (x) {
    // . . . this code is executed
}

This behavior does not apply to Boolean primitives. For example, the condition in the following if statement evaluates to false:

x = false;
if (x) {
    // . . . this code is not executed
}

Do not use a Boolean object to convert a non-boolean value to a boolean value. Instead, use Boolean as a function to perform this task:

x = Boolean(expression);     // preferred
x = new Boolean(expression); // don't use

If you specify any object, including a Boolean object whose value is false, as the initial value of a Boolean object, the new Boolean object has a value of true.

myFalse = new Boolean(false);   // initial value of false
g = new Boolean(myFalse);       // initial value of true
myString = new String("Hello"); // string object
s = new Boolean(myString);      // initial value of true

Do not use a Boolean object in place of a Boolean primitive.

Creating Boolean objects with an initial value of false

bNoParam = new Boolean();
bZero = new Boolean(0);
bNull = new Boolean(null);
bEmptyString = new Boolean("");
bfalse = new Boolean(false);

Creating Boolean objects with an initial value of true

btrue = new Boolean(true);
btrueString = new Boolean("true");
bfalseString = new Boolean("false");
bSuLin = new Boolean("Su Lin");
Documentation for this class comes from MDN and is available under Creative Commons: Attribution-Sharealike license.

Available since: 4.0.0

Defined By

Methods

new( value ) : Boolean
Creates a new boolean object. ...

Creates a new boolean object.

Available since: 4.0.0

Parameters

  • value : Object

    Either a truthy or falsy value to create the corresponding Boolean object.

Returns

Returns a string of either "true" or "false" depending upon the value of the object. ...

Returns a string of either "true" or "false" depending upon the value of the object. Overrides the Object.prototype.toString method.

The Boolean object overrides the toString method of the Object object; it does not inherit Object.toString. For Boolean objects, the toString method returns a string representation of the object.

JavaScript calls the toString method automatically when a Boolean is to be represented as a text value or when a Boolean is referred to in a string concatenation.

For Boolean objects and values, the built-in toString method returns the string "true" or "false" depending on the value of the boolean object. In the following code, flag.toString returns "true".

var flag = new Boolean(true)
var myVar = flag.toString()

Available since: 4.0.0

Returns

  • String

    The boolean value represented as a string.

Returns the primitive value of the Boolean object. ...

Returns the primitive value of the Boolean object. Overrides the Object.prototype.valueOf method.

The valueOf method of Boolean returns the primitive value of a Boolean object or literal Boolean as a Boolean data type.

This method is usually called internally by JavaScript and not explicitly in code.

x = new Boolean();
myVar = x.valueOf()      //assigns false to myVar

Available since: 4.0.0

Returns