JS Data type Conversion

JavaScript is a weakly typed language that does not enforce its data type when declaring a variable, and automatically transforms the data type according to the context environment.

1) String value converted to numeric

The number function parseint function (can accept the second argument, specify the binary of the conversion, the default decimal) parsefloat function

var a = number (' 100 ');
alert (a);//100
Alert (typeof (a));//number
var B = parseint (' 100 ');
alert (b);//100
Alert (typeof (b));//number

The above two examples all replace the string value with a value

Implicit conversions of string conversions to numeric values

Alert (typeof (' 1 '));//number
Alert (typeof (' + '));//number

In the subtraction operator, the string value is converted to the value by default

When it comes to addition

var str = ' abc ' + 1;
alert (str); ' ABC1 '
Alert (typeof (str));//string

Converts a value into a string value, a connection to a string

2) value converted to string

Call the string function or the ToString method

var a = String (100);
Alert (typeof (a));//string
var B = (+). toString ();
Alert (typeof (b));//string

Implicit conversions of numeric conversions to strings

When it comes to addition

var str = ' abc ' + 1;
alert (str); ' ABC1 '
Alert (typeof (str));//string

Customary methods

Convert string value to numeric

var a = ' 1 ';
Alert (typeof (+a));//number

numeric conversions to String values

var b = 1 + ";
Alert (typeof (b));//string

3) Convert other types to Boolean types

Value 0 value nan null value undefined value null string ' This 5 value will be converted to false when implicit conversion other values are converted to true

if (0) {

}

We can use!! For implicit data-type conversions

！ is a Boolean operation of the logical non-operator, you can convert the operand to a Boolean type if it is not a Boolean, so pass!! You can complete the conversion of the Boolean type

JS Data type Conversion