refactor: replace deprecated String.prototype.substr() (#3590)

.substr() is deprecated so we replace it with .slice() which works similarily but isn't deprecated

Signed-off-by: Tobias Speicher <rootcommander@gmail.com>

Signed-off-by: Tobias Speicher <rootcommander@gmail.com>
Co-authored-by: ylemkimon <y@ylem.kim>

src/Parser.js

@@ -922,7 +922,7 @@ export default class Parser {
                     `Accented Unicode text character "${text[0]}" used in ` +
                     `math mode`, nucleus);
             }
-            text = unicodeSymbols[text[0]] + text.substr(1);
+            text = unicodeSymbols[text[0]] + text.slice(1);
         }
         // Strip off any combining characters
         const match = combiningDiacriticalMarksEndRegex.exec(text);

src/buildCommon.js

@@ -190,7 +190,7 @@ const makeOrd = function<NODETYPE: "spacing" | "mathord" | "textord">(
             return makeSymbol(text, fontName, mode, options,
                 classes.concat(fontClasses));
         } else if (ligatures.hasOwnProperty(text) &&
-                   fontName.substr(0, 10) === "Typewriter") {
+                   fontName.slice(0, 10) === "Typewriter") {
             // Deconstruct ligatures in monospace fonts (\texttt, \tt).
             const parts = [];
             for (let i = 0; i < text.length; i++) {

src/buildMathML.js

@@ -32,8 +32,8 @@ export const makeText = function(
     if (symbols[mode][text] && symbols[mode][text].replace &&
         text.charCodeAt(0) !== 0xD835 &&
         !(ligatures.hasOwnProperty(text) && options &&
-          ((options.fontFamily && options.fontFamily.substr(4, 2) === "tt") ||
-           (options.font && options.font.substr(4, 2) === "tt")))) {
+          ((options.fontFamily && options.fontFamily.slice(4, 6) === "tt") ||
+           (options.font && options.font.slice(4, 6) === "tt")))) {
         text = symbols[mode][text].replace;
     }
 

src/environments/array.js

@@ -256,7 +256,7 @@ function parseArray(
 // Decides on a style for cells in an array according to whether the given
 // environment name starts with the letter 'd'.
 function dCellStyle(envName): StyleStr {
-    if (envName.substr(0, 1) === "d") {
+    if (envName.slice(0, 1) === "d") {
         return "display";
     } else {
         return "text";

src/functions/enclose.js

@@ -20,7 +20,7 @@ const htmlBuilder = (group, options) => {
     const inner = buildCommon.wrapFragment(
         html.buildGroup(group.body, options), options);
 
-    const label = group.label.substr(1);
+    const label = group.label.slice(1);
     let scale = options.sizeMultiplier;
     let img;
     let imgShift = 0;

src/functions/mclass.js

@@ -75,7 +75,7 @@ defineFunction({
         return {
             type: "mclass",
             mode: parser.mode,
-            mclass: "m" + funcName.substr(5), // TODO(kevinb): don't prefix with 'm'
+            mclass: "m" + funcName.slice(5), // TODO(kevinb): don't prefix with 'm'
             body: ordargument(body),
             isCharacterBox: utils.isCharacterBox(body),
         };

src/functions/op.js

@@ -61,7 +61,7 @@ export const htmlBuilder: HtmlBuilderSupSub<"op"> = (grp, options) => {
         if (group.name === "\\oiint" || group.name === "\\oiiint") {
             // No font glyphs yet, so use a glyph w/o the oval.
             // TODO: When font glyphs are available, delete this code.
-            stash = group.name.substr(1);
+            stash = group.name.slice(1);
             group.name = stash === "oiint" ? "\\iint" : "\\iiint";
         }
 

src/macros.js

@@ -447,7 +447,7 @@ defineMacro("\\dots", function(context) {
     const next = context.expandAfterFuture().text;
     if (next in dotsByToken) {
         thedots = dotsByToken[next];
-    } else if (next.substr(0, 4) === '\\not') {
+    } else if (next.slice(0, 4) === '\\not') {
         thedots = '\\dotsb';
     } else if (next in symbols.math) {
         if (utils.contains(['bin', 'rel'], symbols.math[next].group)) {

src/stretchy.js

@@ -191,7 +191,7 @@ const svgSpan = function(
         height: number,
     } {
         let viewBoxWidth = 400000;  // default
-        const label = group.label.substr(1);
+        const label = group.label.slice(1);
         if (utils.contains(["widehat", "widecheck", "widetilde", "utilde"],
             label)) {
             // Each type in the `if` statement corresponds to one of the ParseNode