katex/src/utils.js

/**
 * This file contains a list of utility functions which are useful in other
 * files.
 */

/**
 * Provide an `indexOf` function which works in IE8, but defers to native if
 * possible.
 */
var nativeIndexOf = Array.prototype.indexOf;
var indexOf = function(list, elem) {
    if (list == null) {
        return -1;
    }
    if (nativeIndexOf && list.indexOf === nativeIndexOf) {
        return list.indexOf(elem);
    }
    var i = 0;
    var l = list.length;
    for (; i < l; i++) {
        if (list[i] === elem) {
            return i;
        }
    }
    return -1;
};

/**
 * Return whether an element is contained in a list
 */
var contains = function(list, elem) {
    return indexOf(list, elem) !== -1;
};

/**
 * Provide a default value if a setting is undefined
 */
var deflt = function(setting, defaultIfUndefined) {
    return setting === undefined ? defaultIfUndefined : setting;
};

// hyphenate and escape adapted from Facebook's React under Apache 2 license

var uppercase = /([A-Z])/g;
var hyphenate = function(str) {
    return str.replace(uppercase, "-$1").toLowerCase();
};

var ESCAPE_LOOKUP = {
    "&": "&amp;",
    ">": "&gt;",
    "<": "&lt;",
    "\"": "&quot;",
    "'": "&#x27;",
};

var ESCAPE_REGEX = /[&><"']/g;

function escaper(match) {
    return ESCAPE_LOOKUP[match];
}

/**
 * Escapes text to prevent scripting attacks.
 *
 * @param {*} text Text value to escape.
 * @return {string} An escaped string.
 */
function escape(text) {
    return ("" + text).replace(ESCAPE_REGEX, escaper);
}

/**
 * A function to set the text content of a DOM element in all supported
 * browsers. Note that we don't define this if there is no document.
 */
var setTextContent;
if (typeof document !== "undefined") {
    var testNode = document.createElement("span");
    if ("textContent" in testNode) {
        setTextContent = function(node, text) {
            node.textContent = text;
        };
    } else {
        setTextContent = function(node, text) {
            node.innerText = text;
        };
    }
}

/**
 * A function to clear a node.
 */
function clearNode(node) {
    setTextContent(node, "");
}

module.exports = {
    contains: contains,
    deflt: deflt,
    escape: escape,
    hyphenate: hyphenate,
    indexOf: indexOf,
    setTextContent: setTextContent,
    clearNode: clearNode,
};