JavaScript Advanced Programming--Learn from scratch (2)

ECMAScript Foundation

1, grammar

Simple.

2, variable

Use the var operator to add a variable name definition.

If the variable name is not declared, the ECMAScript interpreter creates a global variable with the variable.

Using "Use strict" is recommended to develop good habits and always declare all variables.

3, original value and reference value

In ECMAScript, variables can hold two types of values:

(1) Original value: is a simple data segment stored in the stack, whose values are stored directly in the location where the variable is accessed.

(2) Reference value: An object stored in the heap, that is, the value stored at the variable is a pointer (point) to the memory of the storage object.

JavaScript Advanced Programming--Learn from scratch (2)