Here are a collection of useful TypeScript utility methods. I frequently use these utility methods in my Angular project work and I hope you find it useful as well. You can suggest any useful TypeScript utility methods in the comment section so that I can add it to this list.

Note that each method is a static method so you can access each method with a class name like:

Utils.isObject(null);
Utils.checkEmptyObject("");

For more explanation, please refer comments on each method would be self-descriptive.

Check out JavaScript utility methods at JavaScript Utility Methods

TypeScript Utility Methods

export class Utils {

    /**
     * 
     * @param val Check for null Object
     */
    public static isObject(val) {
        if (val === null) { 
            return false; 
        }
        return ((typeof val === 'function') || (typeof val === 'object'));
    }

    /**
     * Parse JSON string
     */
    public static parseJSON(data) {
        data = data || "";
        return JSON.parse(data);
    }

    /**
     * Check empty object
     */
    public static checkEmptyObject(obj) {
        for (var key in obj) {
            if (obj.hasOwnProperty(key))
                return false;
        }
        return true;
    }

    /**
     * Check if the string is empty or null
     */
    public static checkNotNullAndNotEmpty(data) {
        if (data !== null && data !== '') {
            return true;
        }
        return false;
    }

    /**
      * Check if the variable is undefined
      */
    public static isUndefined(data) {

        if (data === "undefined") {
            return true;
        }
        return false;
    }


    /**
      * Searches for a given substring
      */
    public static contains(str, substring, fromIndex) {
        return str.indexOf(substring, fromIndex) !== -1;
    }

    /**
      * "Safer" String.toLowerCase()
      */
     public static lowerCase(str) {
        return str.toLowerCase();
    }

    /**
     * "Safer" String.toUpperCase()
     */
    public static upperCase(str) {
        return str.toUpperCase();
    }

    /**
     * UPPERCASE first char of each word.
     */
    public static properCase(str) {
        return this.lowerCase(str).replace(/^\w|\s\w/g, this.upperCase);
    }

    /**
     * UPPERCASE first char of each sentence and lowercase other chars.
     */
    public static sentenceCase(str) {
        // Replace first char of each sentence (new line or after '.\s+') to
        // UPPERCASE
        return this.lowerCase(str).replace(/(^\w)|\.\s+(\w)/gm, this.upperCase);
    }
}

Check out JavaScript utility methods at JavaScript Utility Methods.

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