1. String conversion: Convert other data types into strings, which can be used for operations such as splicing strings and outputting results. 2. Number conversion: Convert other data types into numbers, which can be used for mathematical calculations, size comparisons and other operations. 3. Boolean value conversion: Convert other data types into Boolean values, which can be used for conditional judgments, logical operations and other operations. 4. Object conversion: Convert other data types into objects, which can be used to access the properties and methods of the objects. 5. Array conversion: Convert other data types into arrays, which can be used to traverse and operate data.