Snippet

Comparing LaTeX and JSON

• LaTeX code: the text inserted into a .tex file when a snippet expands.
• Snippet definition: the JSON entry saved in latex.json.

A JSON string escapes a backslash by doubling it. The LaTeX command below begins with one backslash in a .tex file and two in the latex.json snippet body.

\begin{equation*}

"\\begin{equation*}"

$1, $2, and $3 are input positions visited in order with Tab. $0 marks the final cursor position, and ${1:label} supplies label as the default text at the first position.

To store multiple snippet definitions in latex.json, place them inside the outer { ... } object and separate entries with commas.

Use the delimiter, matrix, and integral snippets inside math mode. The equation*, align, and cases snippets insert a full display environment.

The bmatrix, equation*, align, cases, and \text examples require amsmath. For \mathbb{R}, load amsfonts or amssymb.

Math delimiters

Use these LaTeX patterns for common math delimiters.

\left\| x \right\|
\left\vert x \right\vert
\left\langle x \right\rangle

Put these snippet entries in latex.json.

"norm": {
  "prefix": "@11",
  "body": "\\left\\| $1 \\right\\| $0"
},
"absolute value": {
  "prefix": "@1",
  "body": "\\left\\vert $1 \\right\\vert $0"
},
"angle brackets": {
  "prefix": "@<",
  "body": "\\left\\langle $1 \\right\\rangle $0"
}

Math structures

Use this LaTeX pattern for a 2×2 matrix.

\begin{bmatrix}
    a & b \\
    c & d
\end{bmatrix}

Put this snippet entry in latex.json.

"2x2 Matrix": {
  "prefix": "mtx2",
  "body": [
    "\\begin{bmatrix}",
    "    ${1:a} & ${2:b} \\\\",
    "    ${3:c} & ${4:d}",
    "\\end{bmatrix}$0"
  ]
}

Use this LaTeX pattern for a definite integral.

\int_{a}^{b}  f(x)  \, dx

Put this snippet entry in latex.json.

"Integration": {
  "prefix": "int",
  "body": "\\int_{${1:a}}^{${2:b}}  ${3:f(x)}  \\, d${4:x} $0"
}

Display equations

Use this pattern for a single displayed equation without a number.

\begin{equation*}
    ...
\end{equation*}

Put this snippet entry in latex.json.

"Equation without numbering": {
  "prefix": "eq",
  "body": [
    "\\begin{equation*}",
    "    $0",
    "\\end{equation*}",
    ""
  ]
}

Type eq and select its snippet suggestion to insert the equation* environment with the cursor inside it.

For an equation you will reference elsewhere, use numbered equation with a \label{...}.

\begin{equation}    \label{eq:main-estimate}
    ...
\end{equation}

Put this snippet entry in latex.json.

"Equation with numbering": {
  "prefix": "eqn",
  "body": [
    "\\begin{equation}    \\label{eq:${1:main-estimate}}",
    "    $0",
    "\\end{equation}",
    ""
  ]
}

After inserting eqn, edit the label after eq: at the first stop. Tab then moves to the final cursor position inside the equation.

Alignments

Use this LaTeX pattern for a multi-line calculation without equation numbers.

\begin{align*}
    f(x)
    &= g(x) \\
    &= h(x)
\end{align*}

Put this snippet entry in latex.json.

"Align without numbering": {
  "prefix": "ag",
  "body": [
    "\\begin{align*}",
    "    $1",
    "    &${2:=} $3   \\\\",
    "    &${4:=} $5",
    "\\end{align*}",
    "",
    "$0"
  ]
}

Four backslashes in a latex.json body string become two in the .tex file. align uses this command to end a row.

Use this LaTeX pattern when the important lines need labels.

\begin{align}
    ...
    &= ...    \label{ag:first-step}    \\
    &= ...    \label{ag:second-step}
\end{align}

Put this snippet entry in latex.json.

"Align with numbering": {
  "prefix": "agn",
  "body": [
    "\\begin{align}",
    "    $1",
    "    &${2:=} $3    \\label{ag:${4:first-step}}    \\\\",
    "    &${5:=} $6    \\label{ag:${7:second-step}}",
    "\\end{align}",
    "",
    "$0"
  ]
}

Use align* when you do not need numbered lines. To refer to a specific line, use align and add a \label{...} to that line.

Theorem blocks and proofs

Use this pattern after defining theorem in the preamble with \newtheorem{theorem}{Theorem}.

\begin{theorem}    \label{thm:main-result}
    ...
\end{theorem}

Put this snippet entry in latex.json.

"Theorem": {
  "prefix": "thm",
  "body": [
    "\\begin{theorem}    \\label{thm:${1:main-result}}",
    "    $0",
    "\\end{theorem}",
    ""
  ]
}

If the preamble defines definition, proposition, lemma, or corollary, you can reuse this snippet structure. Change the environment name, snippet name and prefix, and label prefix together.

Use this pattern for the proof environment provided by amsthm.

\begin{proof}
    ...
\end{proof}

Put this snippet entry in latex.json.

"Proof": {
  "prefix": "pf",
  "body": [
    "\\begin{proof}",
    "    $0",
    "\\end{proof}"
  ]
}

Use label prefixes such as thm:, lem:, prop:, def:, and crl: so the target is easy to identify in the LaTeX source.

Cases and piecewise definitions

Use this LaTeX pattern for a two-case definition.

\begin{equation*}
    f(x) =
    \begin{cases}
        ...    &    \text{if } ...,    \\
        ...    &    \text{if } ...
    \end{cases}
\end{equation*}

Put this snippet entry in latex.json.

"Two cases": {
  "prefix": "css2",
  "body": [
    "\\begin{equation*}",
    "    ${1:f(x)} =",
    "    \\begin{cases}",
    "        $2    &    \\text{${3:if} } $4,    \\\\",
    "        $5    &    \\text{${6:if} } $7",
    "    \\end{cases}",
    "\\end{equation*}",
    "$0"
  ]
}

If a condition is long, explain it before the display and keep each cases row concise.

Figures

Use this figure pattern when the document loads graphicx.

\begin{figure}[htbp]
    \centering
    \includegraphics[width=0.8\linewidth]{figure-filename}
    \caption{Caption text}
    \label{fig:main-figure}
\end{figure}

Put this snippet entry in latex.json.

"Inserting a picture": {
  "prefix": "pct",
  "body": [
    "\\begin{figure}[htbp]",
    "    \\centering",
    "    \\includegraphics[width=${1:0.8}\\linewidth]{${2:figure-filename}}",
    "    \\caption{${3:Caption text}}",
    "    \\label{fig:${4:main-figure}}",
    "\\end{figure}",
    "",
    "$0"
  ]
}

The first placeholder sets the fraction of \linewidth; the second supplies the graphics file path. The third sets the caption, and the fourth sets the label after fig:.

Text and math symbols

Use the first pattern in text and the other two in math mode.

Fr\'echet
\mathbb{R}
\qquad\text{and}\qquad

Put these snippet entries in latex.json.

"Frechet": {
  "prefix": "Fre",
  "body": "Fr\\'echet$0"
},
"Real numbers": {
  "prefix": "R",
  "body": "\\mathbb{R}$0"
},
"And in line": {
  "prefix": "qqand",
  "body": [
    "",
    "\\qquad\\text{${1:and}}\\qquad",
    "$0"
  ]
}

Choose distinctive prefixes for short snippets. If a one-letter prefix such as R appears too often in suggestions, add a marker such as @R.

Save patterns you understand as snippets, then check that you can still read and edit the expanded LaTeX.