pdf-lib/es/utils/numbers.js

Create and modify PDF files with JavaScript

// tslint:disable radix
/**
 * Converts a number to its string representation in decimal. This function
 * differs from simply converting a number to a string with `.toString()`
 * because this function's output string will **not** contain exponential
 * notation.
 *
 * Credit: https://stackoverflow.com/a/46545519
 */
export var numberToString = function (num) {
    var numStr = String(num);
    if (Math.abs(num) < 1.0) {
        var e = parseInt(num.toString().split('e-')[1]);
        if (e) {
            var negative = num < 0;
            if (negative)
                num *= -1;
            num *= Math.pow(10, e - 1);
            numStr = '0.' + new Array(e).join('0') + num.toString().substring(2);
            if (negative)
                numStr = '-' + numStr;
        }
    }
    else {
        var e = parseInt(num.toString().split('+')[1]);
        if (e > 20) {
            e -= 20;
            num /= Math.pow(10, e);
            numStr = num.toString() + new Array(e + 1).join('0');
        }
    }
    return numStr;
};
export var sizeInBytes = function (n) { return Math.ceil(n.toString(2).length / 8); };
/**
 * Converts a number into its constituent bytes and returns them as
 * a number[].
 *
 * Returns most significant byte as first element in array. It may be necessary
 * to call .reverse() to get the bits in the desired order.
 *
 * Example:
 *   bytesFor(0x02A41E) => [ 0b10, 0b10100100, 0b11110 ]
 *
 * Credit for algorithm: https://stackoverflow.com/a/1936865
 */
export var bytesFor = function (n) {
    var bytes = new Uint8Array(sizeInBytes(n));
    for (var i = 1; i <= bytes.length; i++) {
        bytes[i - 1] = n >> ((bytes.length - i) * 8);
    }
    return bytes;
};
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