06. Type conversions

Because JavaScript is a loosely typed language, meaning that it's not necessary to predeclare a given variable's type.

This feature, although convenient, can be the source of many bugs. Particularly, you should watch for type conversions, which is when a value of one type turns into another.

In the example below, the string '1' is converted into a number before the expression is evaluated.

'1' > 0  // true

Implicit conversions

An implicit conversion occurs without your explicit consent. For example, when a string and a number are added together with a + operand, the result is a string.

var ageGreeting = "I am " + 9 + " years old." // "I am 9 years old." 

Explicit conversions

In the case you want to change from a number to a string or vice versa, you can do so explicitly.

Number conversions

var numString = "100";
var num = Number(numString); // 100

String conversions

var numString = String(100);  // '100'
Next section: Control Flow

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