Map in JS (including leetcode examples)

Map

JS Provide us with ready-made Map structure , It can be understood as a set of key value pairs

For specific usage, please refer to teacher Ruan Yifeng's article

leetcode Example

It was also used in many places in the section of array map
JS In the array ( contain leetcode Example )＜ Continuous updating ~＞

13. Roman numeral to integer

var romanToInt = function(s) {
    
    let res =0
    let map = new Map([
        ['I',1],
        ['V',5],
        ['X',10],
        ['L',50],
        ['C',100],
        ['D',500],
        ['M',1000],
    ])
    let length = s.length
    for(let i=0;i<length;i++){
    
        let value = map.get(s[i])
        if(i<length&&value<map.get(s[i+1])){
    
            res = res - map.get(s[i])
        }else{
    
            res = res + map.get(s[i])
        }
    }
    return res   
};