get character total number by ...

getCharCountByVar.js

/**
 * @param Array
 * @return Map 
 */
var getCharNumByArray = (arr) => {
    var m = new Map()
    arr.map(i => {
        if (m.get(i) == undefined) {
            m.set(i, 1)
        } else {
            m.set(i, m.get(i)+1)
        }
    })
    return m
}

/**
 * @param String
 * @return Map 
 */
var getCharNumByString = (str) => {
    var m = new Map()
    str.split('').map(i => {
        if (m.get(i) == undefined) {
            m.set(i, 1)
        } else {
            m.set(i, m.get(i)+1)
        }
    })
    return m
}