http://underscorejs.org/docs/underscore.html
源碼與我的實現(xiàn)對比：
function max()
_.max = function(obj, iteratee, context) {
var result = -Infinity, lastComputed = -Infinity,
value, computed;
if (iteratee == null && obj != null) {
obj = isArrayLike(obj) ? obj : _.values(obj);
for (var i = 0, length = obj.length; i < length; i++) {
value = obj[i];
if (value > result) {
result = value;
}
}
} else {
iteratee = cb(iteratee, context);
_.each(obj, function(value, index, list) {
computed = iteratee(value, index, list);
if (computed > lastComputed || computed === -Infinity && result === -Infinity) {
result = value;
lastComputed = computed;
}
});
}
return result;
};
imax = function(list, iteratee, context){
let slist = [];
let maxCursor = -1;
let max = Number.NEGATIVE_INFINITY;
list.forEach(function(n){
let s = iteratee(n);
let sn = Number(s);
if(sn!=NaN){
slist.push(sn);
}
})
for (var i in slist) {
if(slist[i]>max){
max = slist[i];
maxCursor = i;
}
}
return list[maxCursor]
}
ie8 forEach 實現(xiàn)
if(!Array.prototype.forEach){
Array.prototype.forEach = function(fun){
var length = this.length;
for(var i = 0; i<length; i++){
fun.call(this, this[i], i, this)
}}
}
