Javascript Interview Question String Contain unique characters

Introduction

Implement an algorithm to see whether a String has all unique characters. 

function isUniqueChars(str) {
    //your code
}
console.log(isUniqueChars('abcd'));
console.log(isUniqueChars('abbd'));



/**
 * @function {public static} isUniqueChar
 *
 * Finds whether a `String` has all unique chars.
 *
 * @param {String} str - the `String` to test.
 *
 * @return `true` if the `String` has all unique chars, `false` otherwise.
 */
function isUniqueChars(str) {
    var hash = {};

    var i = 0;
    var len = str.length;

    for (i = 0; i < len; i++) {
        if (hash[str[i]]) {
            return false;
        }

        hash[str[i]] = true;
    }

    return true;
}
console.log(isUniqueChars('abcd'));
console.log(isUniqueChars('abbd'));

/*
Output: ($ /usr/bin/node 005.js)
true
false
*/



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