# Macros
Over [800 LaTeX commands](/mathfield/reference/commands/)
are predefined. Some are primitives but others are macros, that is commands defined
with a LaTeX expression. You can define your own macros.
## Adding/Removing Macros
**To add a macro** use `mf.macros = {...mf.macros, ...}`.
If you do not include the `...mf.macros` expression, all the standard macros will be
turned off.
The example below will define a new command, `\average`, which will be
replaced by `\operatorname{average}`, that is displayed as a single unit
using an upright font.
Try changing `\operatorname` to `\mathbf` to see the difference.
```live show-line-numbers mark-line=3
:::html
\average([2, 4, 8])
:::js
const mf = document.getElementById("mf");
mf.macros = { ...mf.macros,
average: '\\operatorname{average}',
};
```
You can use standard LaTeX commands in the definition of a macro. For example,
the following macro definition uses the `\,` and `\;` commands to insert
horizontal spacing and `{}^` to place the `\prime` command on the subscript
line.
```javascript
mf.macros = { ...mf.macros,
minutes: "\\,{}^\\prime\\;",
seconds: "\\,\\doubleprime\\;",
};
```
The macro definition can contain up to eight arguments, represented by `#1` to `#9`.
```live show-line-numbers
:::js
const mf = document.getElementById("mf");
mf.macros = {...mf.macros,
smallfrac: "{}^{#1}\\!\\!/\\!{}_{#2}",
};
:::html
\smallfrac{5}{7}+\frac{5}{7}
```
By default, a macro command behaves as a group whose subcomponents cannot be
modified. This behavior can be controlled using the `captureSelection` flag
in the expanded definition of a macro.
**To define a macro whose content is selectable and editable** set
`captureSelection` to `false`.
```live show-line-numbers mark-line=6
:::js
const mf = document.getElementById("mf");
mf.macros = {...mf.macros,
smallfrac: {
args: 2,
def: '{}^{#1}\\!\\!/\\!{}_{#2}',
captureSelection: false,
},
};
:::html
\scriptCapitalE=\smallfrac{5}{7}+\frac{5}{7}
```
**To remove a macro** set its definition to undefined:
```live show-line-numbers
:::js
const mf = document.getElementById('mf');
mf.macros = {...mf.macros, diamonds: undefined };
:::html
\diamonds
```
## Adding a Matching Shortcut
By defining a new macro, a new LaTeX command is added to the dictionary
of commands that can be used in a LaTeX expression.
To input a macro, type \\ followed by the macro name, then RETURN
Custom macros are also included in the value of the mathfield
expressed as a LaTeX string (`mf.value`).
It may also be convenient to associate the macro with an inline
shortcut. Inline shortcuts can be typed without having to enter the LaTeX
editing mode (without having to type the \\ key).
**To define an associated inline shortcut**, use the `inlineShortcuts` option.
```live show-line-numbers
:::js
const mf = document.getElementById('mf');
//
mf.macros = {...mf.macros,
// This means that the command macro `\minutes`
// will be replaced with `\,{}^\\prime\\;`
minutes: '\\,{}^\\prime\\;',
seconds: '\\,\\doubleprime\\;',
};
//
mf.inlineShortcuts = {...mf.inlineShortcuts,
// This means that typing the inline shortcut
// "minutes" will insert the command "\minutes"
minutes: '\\minutes',
seconds: '\\seconds',
};
:::html
3\minutes 15\seconds
```
## Inspecting Available Macros
**To view the available macros**, inspect the `macros` property:
```live show-line-numbers
:::js
const mf = document.getElementById('mf');
console.log(mf.macros);
:::html
x=\frac{-b\pm \sqrt{b^2-4ac}}{2a}
```
## Disabling Macros
**To turn off all macros**, use `mf.macros = {}`.