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JavaScript Code

var str = "hi";

Memory allocation:

Address Value Description
...... ...
0x1001 call object Start of a call object's memory
0x1002 0x00af Reference to invoked function
0x1003 1 Number of references in this call object
0x1004 str Name of variable (in practice would not be in a single address)
0x1005 0x1001 Memory address of "hi"
...... ...
0x2001 string type identifier
0x2002 2 number of bytes
0x2003 h byte of first character
0x2004 i byte of second character

Explanation

When JS runs: var str = "hi"; by calling some function, it first hoists all variable declarations and creates a spot in memory for the variable. This might leave memory something like:

Address Value Description
...... ...
0x1001 call object Start of a call object's memory
0x1002 0x00af Reference to invoked function
0x1003 1 Number of references in this call object
0x1004 str Name of variable
0x1005 empty
...... ...

In practice, the name of the variable, str, would not be held in a single memory address. Also, the variable names and locations would not be stored in a fixed-memory array (possibly in a hash-table).

Next, the string "hi" would be created in memory like:

Address Value Description
...... ...
0x2001 string type identifier
0x2002 2 number of bytes
0x2003 h byte of first character
0x2004 i byte of second character

Finally, the pointer address of str would be set to the memory address of "hi" (0x2001), leaving memory as indicated at the top of the page.

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